'It's just rubble,' witness says

• Apparent explosion in Manhattan's East Harlem


• Eleven minor injuries were reported


• Metro North commuter rail service suspended

Editor's note: Are you nearby? Share photos, videos of the scene with CNN iReport if you can do so safely

(CNN) -- New York police and fire officials were responding to reports of a massive explosion in Manhattan's East Harlem, authorities said Wednesday.

There were at least 11 minor injuries as clouds of dark smoke rose over the residential neighborhood of red-brick tenements, fire officials said.

Metro North commuter rail service, which runs along the site of the blast on Park Avenue, was suspended, officials said.

"Two buildings have collapsed. I hope there is no one in there. It's just rubble," a worker at a nearby flea market said.

Clouds of dark smoke could be seen for a three-block radius as hundreds of rescue officials descended on the scene.

CNN first learned of this story via Twitter.