Social media "pop-up party" caused public safety emergency, curfew in Long Branch, N.J.

LONG BRANCH, N.J. -- A social media post advertising a "pop-up party" on Saturday caused a public safety emergency in Long Branch, New Jersey as thousands of people converged around Pier Village, Monmouth County authorities said on Sunday.

The crowd was estimated to include "several thousand people" at certain points and multiple fights broke out among the partygoers, officials said in news release.

Officials said multiple agencies responded. A flash bang was deployed and smoke was used to disperse the crowd in areas where bottles and rocks were reportedly being thrown.

A curfew went into effect at 9 p.m. in Long Branch and was lifted at 6 a.m.

The "vast majority" of partygoers "left peacefully" when the curfew was announced, according to officials. Most had arrived by train, they said. 

Eleven adults and four juveniles were arrested.

A police vehicle was vandalized, but there were no reports of significant injuries or additional property damage, officials said.