The shocking Facebook videos, which the police have asked not to be shared, show young girls kicking, punching and pulling the hair of a number of victims in daylight attacks in Ashington.
Chief Inspector Helena Barron, of Northumbria Police, said: “We are aware of footage circulating on social media regarding an assault in Ashington.
“Officers are trying to identify the victims and offenders involved, and will take robust action against anybody found to be participating in this unlawful activity.
“Four youths have been arrested in connection with this incident and released under investigation pending further inquiries.
“We would encourage people not to share these videos on social media to protect the victims and would advise any footage to be sent to the police to assist with the ongoing investigation.
“Anybody with footage, or who has more information, should contact police at 101, quoting reference 1078 030518.”