Hundreds of teenagers stormed and trashed a Brooklyn, N.Y., mall in a wild flash mob that forced the shopping center to close its doors during day-after Christmas sales, sources said on Friday.

More than 400 crazed teens grabbed and smashed jars of candy, stole cheap items such as baby balloons and beat up security guards at Kings Plaza Shopping Center in Mill Basin between 5 p.m. and 7 p.m., merchants said.

A violent game of “Knockout” also broke out on the upper level of the mall — and one teen may have been carrying a gun, sources said.

The teens used social media to plan the mass looting, vowing to put the mall “on tilt” – or to raid it, according to posts on Facebook and Twitter.

Clerks, who scrambled to close up their shops, said they were terrified.

“I’ve been here seven years and I have never seen anything like this before — I’m so scared. I know they will come back,” said Abu Tabel,31, a clerk at Candy Plaza 2.

“I was begging them to stop. There were a lot of kids hundreds of kids… [Security] would chase them out one door and they would come back in another door.”

Clerks at shops such as Macy’s, Victoria’s Secret and Mac quickly rolled down metal gates as security guards tried desperately to break up the mob. The mall was closed for roughly an hour around 7 p.m., sources said.

Violent fights also broke out in front of McDonald’s and Best Buy, sources said. Video footage shows a pack of teenage girls punching each other and screaming as security guards struggled to break up the brawl.

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