Teenagers fighting over high school vendettas end up being responsible for around 40 percent of New York City's shootings, police say.

The NYPD says it has identified more than 300 teen crews made up of 12-18-year-olds who call themselves names like the Very Crispy Gangsters, True Money Gang and Cash Bama Bullies and tend to post about their affiliations on social media.

(In recent years, the NYPD has stepped up online investigations, creating fake profiles of attractive women to monitor teen gang members online.)

Police say many of the crews are hypersensitive to perceived slights, especially on the internet, and tend to react with sweeping violence.

The most notable recent case came in March when investigators say a 14-year-old member of the Stack Money Goons shot a .357 revolver at a rival member of the Twan Family on a crowded bus in Brooklyn. The bullet instead killed an immigrant father who was working two jobs to support his family.

Authorities say it doesn't help that teenage gang members who end up serving time tend to leave prison as "a sort of hybrid gang-crew combination with diffused connections and alliances."

"It's like belonging to an evil fraternity," the commander of the New York Police Department's gang division told the AP.

[image via Shutterstock]