Police across Wales have been preparing to stamp out anti-social behaviour associated with Halloween.
Police, parents and shops hope to tackle anti-social behaviour
Forces were gearing up for Monday night's celebrations, with extra officers planned for many areas.
They had warned that those who cross the line could be issued with Penalty Notices for Disorder (PNDs) - carrying fines of up to £5,000 or even jail.
PNDs can be given for firework offences, and officers have watched for people breaking new "curfew" rules.
Chief Superintendent Graham Davies, of South Wales Police, had said Halloween and Bonfire Night were the most demanding nights for police, and were rapidly becoming a celebration lasting weeks.
"Whilst this time can be fun for the majority of people, there are some who will use these weeks as an excuse for unacceptable, dangerous, and often criminal behaviour," he added.
"This year, we will be using powers available to us to target those who cross that line and issuing Penalty Notices for Disorder (PNDs), which could potentially cost those who go too far up to a £5,000 fine or even time in prison."
PNDs can be issued to people if they:Breach the 2300 GMT to 0700 GMT rule - the times between which fireworks cannot be used on HalloweenPossession of an "adult" firework in a public place by someone under 18Possession of a firework meant only for professional display.
"There is a fine line between enjoying yourself with your friends and your fun impinging on others," Mr Davies added.
Gwent Police said extra patrols were being organised in some areas.
In Newport, officers had increased high visibility patrols, following concerns from some householders who say they had been intimidated by gangs of youths with eggs, flour and fireworks.
Traders have been asked not to sell flour and eggs to children
The city's council had also produced posters for householders who do not want to be visited by "trick or treaters" to display.
Letters were sent to schoolchildren advising them to take part in Halloween and Bonfire Night activities in a "safe and sensible" manner.
'It is important that we take action in advance of events such as this to minimise any potential anti-social behaviour that could have an impact on our communities," said Inspector Alun Webber.
"This is not about spoiling fun, but ensuring everybody is able to enjoy this period of the year in a safe and responsible manner."
South Wales Fire and Rescue Service had also urged the public to remember fire safety messages at Halloween.