Firefighters battle a fire after a building collapses in the East Harlem neighborhood of New York, Wednesday, March 12, 2014 (AP Photo/John Minchillo)

Two buildings collapsed in East Harlem on Wednesday morning after a massive explosion, leaving at least six people dead.

The buildings, which collapsed around 9:30 a.m., were located at 1644 and 1646 Park Avenue, between 116th and 117th streets. Local hospitals treated at least 69 people for injuries, according to NBC New York. The Associated Press reported that as of Wednesday evening, there were still nine people missing.

One of the victims was identified as Griselde Camacho, 44, a public safety sergeant at Hunter College. The school's president, Jennifer Raab, confirmed Camacho's death in a statement, saying, "our hearts go out to Griselde's family at this terrible time."

Dental hygienist Carmen Tanco, 67, Rosaura Hernandez Barrios, 22, and three others also perished in the building collapse, The New York Times reported. The last three victims were discovered overnight and have not yet been identified.

New York City Mayor Bill de Blasio said at a press conference that the explosion was caused by a gas leak. In a statement to the New York Daily News, Con Edison confirmed that neighbors called in to complain about the smell of gas just 18 minutes before the explosion.

“This is a tragedy of the worst kind because there was no indication in time to save people,” de Blasio said.

The New York City Fire Department responded to a 5-alarm fire at the scene of the collapse.

"The way the building imploded after the explosion, it must have happened on the bottom floor," said Carmen Vargas-Rosa, an employee at the Spanish Christian Church located in one of the buildings that collapsed. "The only thing I can see doing that much damage is a gas explosion."

Vargas-Rosa said she hadn't heard from many of the tenants who lived in the apartments above the church. She said at least 14 tenants and their children lived in the buildings.

"We could feel the boom," said neighbor Gus Cortez, 36. "We ran outside and we could see that the buildings had fallen. There was a lot of fire. People were scared."

The blast occurred near the Metro-North train tracks in Harlem, and service was suspended in and out of Grand Central Terminal as workers cleared debris. Trains were up and running again by the afternoon.

This is a developing story. Live updates below:

