The government reckons the gun problem affects lots of young people, who carry weapons either to protect themselves or look cool.
Carrying guns is also sometimes related to drugs.
'It has got to stop'
Marcia Shakespear, the mother of one of the girls who died, said something must be done to stop the gun culture.
"This has got to end," she said. "My daughter's life was cut short by this incident. I do not want another child to be killed.
It has got to stop now."
The government is hosting talks with police and other relevant groups on Friday to discuss how best to tackle the growing gun problem in Britain.