MILL BASIN, Brooklyn — A fast-growing fire burned through the parking garage of Kings Plaza Shopping Center in Brooklyn on Monday, injuring 21 people, authorities said.

Multiple vehicles caught on fire on two floors of the four-story parking garage, located at 5100 Kings Plaza, according to the FDNY.

FDNY Commissioner Daniel Nigro said about 120 cars were stored on the second floor of the parking garage by a local dealership. It was not immediately known how many cars caught on fire.

In a tweet, Kings Plaza said the mall is currently closed and told the public to avoid the area.

The fire broke out shortly before 9 a.m. and three hours later, it was still burning.

Dark plumes of smoke were billowing from the structure and could be seen from miles away.

Eighteen firefighters and 3 civilians were hurt, according to Nigro. All of them suffered non-life-threatening injuries.

“Members have various levels of smoke inhalation and heat exhaustion, working under these conditions,” FDNY said in a tweet.

The fire is being investigated as “suspicious,” sources told PIX11 News. Police released a picture of a person of interest connected to the fire.

Anyone with information is asked to contact police.

Task force members from the Bureau of Alcohol, Tobacco, Firearms and Explosives were on scene investigating.

Huge fire in Kings Plaza mall parking lot. #Brooklyn pic.twitter.com/1KfHYzwvKx — Jon Sosis (@FunnyJS) September 17, 2018