At least four New York City firefighters and a dozen people have been injured after a building explosion in a Chinatown hair salon caused part of the building to collapse, the Daily News reports. Two of the people injured are reportedly in critical condition.

The blast happened around 12:45 p.m. at 17 Pike St inside the downstairs Piao Liang Ren Scheng Beauty Salon. A police source told the Daily News that the explosion was apparently caused by roach bombs that were not being used properly. Fire investigators found boxes of Raid fumigating foggers and Decon bug bombs in the salon, the newspaper reports. Officials are also investigating whether a possible gas leak was involved in the blast.

On top of the first-floor hair salon are apartments. Soon after the explosion the apartments quickly began to fill with smoke and flames panicking the residents. When fire crews arrived people were standing on balcony's begging for help after being trapped in their apartments.

"It sounded like a truck smashed into a building," Jahleel Mazyck, 13, told the newspaper.

Tszkan Cheung, a resident of the building, told CBS that he was eating lunch at the time of the explosion. He described the noise as a "boom, like a bombing, like an earthquake" saying that he made it out of his apartment safely but did see firefighters carrying people out.

Another resident Jinjoo Yang said the smoke smelled of gas and at first she wasn't sure what the noise was.

"I heard a big sound. It sounded like something big fell from the next floor," she said. "I felt the whole floor shaking."

Victims from the fire have been taken to New York Presbyterian/Well Medical Center and Bellevue Hospital to be treated.