NEW YORK (AP) — A thunderous explosion that may have been caused by a gas leak flattened two East Harlem apartment buildings Wednesday, killing at least two people, injuring 18 and leaving an undisclosed number missing.

Utility workers were on the way to check out a report of a gas odor at the time of the 9:30 a.m. blast, which shattered store windows for blocks, hurled debris onto elevated commuter railroad tracks close by, cast a plume of smoke over the skyline and sent people running into the streets.

The two five-story brick buildings on Park Avenue at 116th Street were reduced to a burning heap of bricks and metal.

"It felt like an earthquake had rattled my whole building," said Waldemar Infante, a porter who was working in a basement nearby. "There were glass shards everywhere on the ground, and all the stores had their windows blown out."

Police said two females died, but they had no further details.

Mayor Bill de Blasio said authorities were trying to locate "a number of missing individuals," some of whom may have fled to safety.

Con Edison had received a report of a gas leak 15 minutes before the explosion, de Blasio said. The blast occurred before the Con Edison team arrived, according to the mayor.

The East Harlem neighborhood stood at a standstill as police set up barricades to keep residents away. Thick, acrid smoke rose into the air, causing people's eyes to water. Some wore surgical masks, while others held their hands or scarves over their faces.

Sidewalks for blocks around were littered with broken glass. Witnesses said the blast at Park Avenue and 116th Street was so powerful it knocked groceries off the shelves of nearby stores.

One of the side-by-side Park Avenue buildings had a piano store on the first floor, the other a storefront church. Building Department records don't show any work in progress at either address, but the building with the church had obtained permits to install new gas pipes in June.

A resident of the one of the buildings, Eusebio Perez, heard news of the explosion and hurried back from his job as a piano technician.

"There's nothing left," he said. "Just a bunch of bricks and wood."

Perez, 48, said he shared an apartment with a roommate and was unsure what his next steps would be.

"I only have what I'm wearing," he said. "I have to find a place to stay for tonight and organize what's going to be my next steps."

The explosion occurred very close to Metro-North tracks. Metro-North service was suspended commuter train service to and from Grand Central on all its lines while employees removed debris from the tracks.

___

Associated Press Reporters David B. Caruso, David Crary, Leanne Italie and Meghan Barr contributed to this report.