By Chris Francescani
NEW YORK, March 12 (Reuters) - Two buildings collapsed in an explosion in Upper Manhattan on Wednesday, killing at least one person, injuring at least 17 and setting off a search for anyone trapped in the debris, witnesses and officials said.
Massive clouds of smoke billowed from the charred rubble of the adjacent five-story structures which reportedly collapsed shortly after 9 a.m. (1300 GMT)on the largely residential block at East 116th Street and Park Avenue in East Harlem.
Residents said the fiery collapse of the apartment buildings atop ground-level businesses - a church and a piano store - was accompanied by a loud boom that could be heard from blocks away and shattered windows around the neighborhood.
"All of the sudden the whole building shook. We had no idea what was going on," said Robert Pauline, 56, a Columbia University data processor whose apartment six blocks away was rocked by the explosion.
Another nearby resident, Chasity Bergos, 23, said she received worried calls from friends who "woke up thinking it was an earthquake."
Police spokesman Martin Speechley said the cause of the explosion was under investigation.
Mayor Bill de Blasio rushed to the scene, where a cascade of twisted and burnt metal blocked the sidewalk and covered parked cars.
President Barack Obama was briefed on the collapse and sent his condolences to the victim families and his support to first responders at the scene.
"Our thoughts and prayers go out to everyone impacted by this incident," the White House said in a statement.
Crowds of residents, their faces covered with protective scarves and masks, filled the sidewalks of surrounding streets, which were blocked off with yellow police tape.
"It's a very active scene. It's a very chaotic scene," said Fire Department spokesman Michael Parrella.
Fire trucks used high cranes to spray blasts of water into the rubble, as dozens of ambulances and police cruisers with flashing lights swarmed the scene.
Commuter trains were stopped on nearby tracks because of the debris on the rails and passengers were ordered off the Metro-North Railroad cars at the Fordham stop in the Bronx, passengers said.