NEW YORK (AP) – A four-story building on Manhattan’s Upper East Side collapsed into a pile of rubble Monday after a thunderous explosion that hurled fireballs high into the sky and left the block covered in bricks, broken glass and splintered wood.

Authorities said they were investigating whether the gas explosion was the result of a suicide attempt by a doctor who owned the building and was going through a bitter divorce.

A police official with direct knowledge of the case told The Associated Press that the man recently sent out a rambling e-mail to his wife in which he contemplated suicide and said, “You will be transformed from gold digger to ash and rubble digger.” The official spoke on condition of anonymity because the investigation is ongoing.

Authorities said at least 15 people were injured in Monday’s explosion, including five civilians and 10 firefighters.

The doctor, 66-year-old Nicholas Bartha, was pulled from the rubble after talking with authorities from his phone while buried in the wreckage, fire commissioner Nicholas Scoppetta said. Bartha and one passer-by suffered severe injuries; the remaining injuries were minor.

“This could have been an even worse disaster than it already is,” Scoppetta said.

The explosion and fire created a horrific scene on the Upper East Side. Heavy black smoke rose high above the landmarked, 19th-century building on 62nd Street between Park and Madison Avenues _ just a few blocks from Central Park. Debris was strewn everywhere. Four of the injured were pedestrians _ some of them found on the street covered in blood.

“In a few seconds, finished,” said Thad Milonas, 57, who was running a coffee cart across from the building and came to the aid of two bloodied women. “The whole building collapsed.”

Scoppetta said authorities were looking into the possibility that the blast was the result of a suicide attempt. “We’re still investigating that, talking about the potential for suicide. So that’s a distinct possibility.”

Officials said Bartha was apparently losing the home because of the divorce, and court records show that he faced a $4 million lien as a result of the case.

Messages left with lawyers for the couple were not immediately returned.

The fire was reported at 8:40 a.m., and hundreds of firefighters rushed to the scene.

Rabbi Yaakov Kermaier, 36, a resident in a building next door, said he was outside when he heard “a deafening boom. I saw the whole building explode in front of me.”

“Everybody started running, nobody knew what was coming next,” said Kermaier, whose nanny and newborn escaped from their apartment unharmed.

Police Lt. Eugene Whyte said the building included two doctor’s offices, and Scoppetta said Bartha was apparently the only person who lived there. Whyte said a nurse who was supposed to open one of the doctors’ offices arrived late, narrowly missing the explosion. The other doctor’s office was run by Dr. Paul Mantia.

Whyte said the medical offices opened at 9 a.m., so no patients were in the building.

TV host Larry King, who had been in his hotel room nearby, described the explosion to CNN as sounding like a bomb and feeling like an earthquake. “I’ve never heard a sound like that,” King said.

Sherry Miller, who lives on the seventh floor of a neighboring building, ran out of her home in her pink bathrobe after the blast. Miller said she “saw coming down in front of my window a big piece of plaster. Then it kept tumbling and tumbling. And what I thought _ I thought it was a bomb. The flames came in a second.”

Streets around the area were closed off to traffic as ambulances and rescue units responded, and the chaos snarled traffic. Dozens of onlookers stood behind police tape, snapping pictures and watching the smoke as it engulfed the Manhattan sky.

The building is located in an upscale neighborhood where the 2000 Census said the median price of a home was $1 million.