Newsround's been investigating the real stories behind the headlines about children who carry knives.
But what do you think about knives and the people who carry them?
Are knives a problem in your school or where you live? Does it make you scared to go out?
Maybe you carry a knife or know someone else who does? Or are knives not a problem at all where you live?
Unfortunately this topic is now closed but there are Comments pages on other subjects on the main Chat index.
"Whoever has a knife is a very big bully."
Stephen McCall, 10, Cornwall, England
"I'm not really 'scared' of knives, but I think they are dangerous and although some people can be trusted, many can't. But I get really annoyed when people blame parents all the time. You have to take responsibility for your own actions."
Jordan, 11, Northumberland, England
"I don't think they should be completely banned because some people use them for good reasons, but I do think they should be banned on the streets."
Ryan, 10, Essex, England
"Most kids who carry knives probably don't buy the knives, they get them from their home."
Eve, 10, Stockport, England
"I think that nobody should have knives, not even play ones, because when you're used to stabbing people playfully with toy knives, who knows what will happen when you get a real one? It just isn't safe."
Brian, 11, Hong Kong
"I think knives have their good side and a bad side. They can help us do something, but they can take someone's life away. If a child is carrying a knife it's the parents' fault."
Chloe, 8, York, England
"I don't think anyone under 20 should be allowed to buy knives."
Joe, 7, Birmingham, England
"I think that those who carry knives feel comforted and protected or possibly even cool, but they must learn that they may feel safe but they are endangering lives"
Caoimhe, 11, Twickenham, England
"People only carry knives to protect themselves but sometimes it gets out of hand and people can die"
Louise, 11, Birmingham, England
"I don't think anybody should carry knives around, it is so dangerous. The government should stop people selling knives or any dangerous equipment!"
Anna, 11, Stockport, England
"Knives should be banned completely and a heavy punishment should be given to anyone who is found carrying a knife. They're just too dangerous."
Winnifred, 11, Belfast, Northern Ireland
"I think that even if knives are taken away or made more expensive, gangs will still manage to find ways of getting their hands on them or find something even worse than knives."
Hannah, 12, Hertfordshire, England
"I don't think knives should be allowed on the streets, but in other cultures they carry around weapons because it's their religion."
Conor, 12, Barnstaple, England
"I think that the people who carry knives should be made to see what the results could be."
Samantha, 11, Midlothian, Scotland
"I think knives have their good side and their bad side. They can help us do something, but they can also take someone's life! If a child is carrying a knife it is their parents' fault. "
Inayah, 12, Leeds, England
"I used to carry a knife for my protection. I also bought a magazine regularly and there was an article explaining the dangers. I understand that a knife puts you in more danger. I hope many others will too."
Simon, 15, Greater Manchester, England
"No-one should carry knives!!!!!"
Nick, 7, Lanarkshire, Scotland
"I think it is stupid and silly because more people are getting killed and then they will go to prison for it."
Chloe, 10, Norwich, England
"I think that knives are good because they can be handy for adults to cut things, but people use them as weapons which is bad."
Mike, 13, Barmouth, England
"When I help my dad cook it freaks me out as I feel that a knife might hurt me, but if people carry them around then it would really scare me."
Amber, 10, Leamington, England
"I think it's silly carrying knives around. It's dangerous and makes other people scared that they could be hurt or killed by teens hanging around at night."
Alice, 10, Sussex, England
"Knives aren't a problem at my school. I think they are dangerous to carry round and usually the people who carry them are horrible big-headed teenagers."
Aimee, 13, London, England
"Some people just have it to feel safe. I think people can't control themselves, and because of that, should not be allowed to carry knives. I was once threatened with a pen knife, and have been scared ever since."
Tanya, 11, Stockton, England
"Knives come in handy for cutting food, but not around the streets! I think knives should be banned from the streets and banned from shops!"
Hannah, 9, Lancashire, England
"They can kill so nobody should be allowed to carry them. There should be security checks from the 7th year at school and above - the government should pay for this to happen."
Ellie, 8, Hertfordshire, England
"When I walk home from school I always watch out because I'm really scared of knives."
Lauren, 12, Jersey, Channel Islands
"I don't think knives are a good idea at all, even though some people say they are for protection. I would never carry one because, even though it could be an accident, someone would get hurt."
Sophie, 10, Belfast, Northern, Ireland
"Knifes are very dangerous. I think there should be a new rule: whoever has a knife should be put in prison for 16-20 years."
Tyler, 9, Kent, England
"I really don't have a problem with knives. I'm sure that people would have a good reason for carrying them... well, at least some of them. I think that the punishments for 14-18-year-olds are too harsh in England."
Safa, 13, London, England
"It's just silly if people think that knives are cool because knives are really dangerous."
Kelly, 9, Auderghem, Belgium
"The price should be put up as they're pathetic. Why carry them?!!! They should have knife checks at schools, work and public areas. Just ban the knives."
Selina, 10, Bath, England
"They are bad and people who carry knives should go to prison."
Marco, 11, Udine, Italy
"I think it is horrible and the people should get help."
Grace, 9, Swindon, England
"I think people who carry knives are bullies or victims who just try to stand up for themselves, but that doesn't change what they have done."
Emma, 9, Glasgow, Scotland
"I think people that use knives for crime are just wasting their time. I also think that people use them because of their friends or what they see on TV."
Rianna, 13, London, England
"Well they can't be banned or we can't really eat stuff. I use a penknife in the garden and for decorating but not on the streets."
Nicola, 11, Cambridge, England
"I feel scared when I am walking down the road because you don't know who has got a knife."
Calvin, 10, Bolton, England
"I think knives should be made harder to buy. They should be more expensive."
Simona, 11, Birmingham, England
"I think that knives are very dangerous and it should be a lot harder to get them, for everyone's safety."
Hannah, 12, Nottinghamshire, England
"People that carry knives are probably scared about other people with knives and if that is what they have in their heads then they should think about the trouble or danger they are making for themselves."
Garnet, 11, London, England
"I think people should not carry knives because it is dangerous and stupid."
Laura, 8, Maidstone, England
"I hate knives and I hate what they can do you."
Charlie, 9, Ashford, England
"I really feel quite bad with people who carry knives as most people would carry them for safety as they don't feel safe on their own."
Jarinne, 13, Berkshire, England
"I hate knives, they scare me when I hear about it on the news."
Shannon, 8, Nottinghamshire, England
"Luckily, where I live, these issues are not a problem. Whoever carries a knife to look cool needs a serious reality check. They haven't thought of all the dangers they face, like having their knife used against them. If random police checks will help keep knives off the streets then we should introduce them straight away."
Jamila, 13, Bedfordshire, England
"Knives are just to scare people, but some feel the need to stab people for protection. If they want to protect themselves they should learn self-defence so people do not end up dead or on life support."
Nay, 11, Brighton, England
"Knives are pathetic, innocent people get stabbed just because of a stupid 'gangster', why would you feel the need to carry one? I feel sorry for the people that do!"
Bex, 12, London, England
"I think that knives and people carrying them are just accidents waiting to happen. I hate knives and people who carry them around or own one."
Heather, 13, Hampshire, England
"Knives should be banned. They are horrible, dangerous things that kill people and wreck families. I don't understand how anyone would want to carry one."
Katy, 12, County Londonderry, Northern Ireland
"I think knives are really dangerous and people get hurt or killed by them."
Oden, 11, Surrey, England
"Knives are horrible; they separate families, cause pain and death. How can people carry them, let alone use them?"
Amira, 12, Bradford, England
"The people who use knives are stupid, they think they are cool. I think they need help because if they had things to do they wouldn't be hanging round scaring people. There should be more activities for people who are bored and have nothing to do but threaten poor, defenceless people in the public."
Sarah, 13, Hertfordshire, England
"Knives are dangerous when used for the wrong reasons, but I do find it very annoying when parents actually buy 4-8 aged children their own. They simply do not know the possible dangers."
Will, 11, Lincoln, England
"There are loads of kids round by ours who have knives. I asked one why and they said 'in case anything happens', but that's just going to attract trouble if you're carrying round a knife. I was once walking home with my sister and some lad from another school was following us and saying very nasty things. He got a penknife out and was waving it about."
Aadrienne, 13, Liverpool, England
"Thankfully knives aren't a problem where I live, so when I watch or hear the news and it involves people being injured via knives it makes me think how lucky I actually am living in a reasonably safe environment. If I lived in an environment in which knives were a problem I'd feel rather insecure."
Laura, 14, Doncaster, England
"Knives are dangerous. People who use them are selfish and only care about themselves. They don't have respect for other people"
Danielle, 11, Caerphilly, Wales
"My cousin is in a gang in London and he has got into two fights and got stabbed. I feel and know that this is wrong for our country because it isn't doing anyone any good. But what can WE do?"
Kori, 11, London, England
"I hate knives. I think gangs influence children because they think it's cool. it's not - it's pathetic."
Demi, 10, London, England
"This boy in my school once got excluded because he brought in a penknife.
I think they are really dangerous and parents should keep an eye on children to see what they are taking to school."
Zaryab, 11, Birmingham, England
"My best friend got stabbed with a knife and she is struggling for her life in hospital.
I think that knives should only be given to adults and no kids should have access to them."
Shannon, 10, London, England
"I think knives are dangerous! I don't think anyone should carry them."
Grace, 9, Norwich, England
"I haven't seen any knives in my area but you still shouldn't carry them. You could get arrested or you could slip and hurt yourself."
Georgia, 11, Cornwall, England
"I don't want to go outside because of gang violence with knives. Now I've started to hear stuff about people being shot, so I feel very insecure."
Mike, 12, London, England