Officials have suspended Second Ave. subway construction after a controlled blast went awry Tuesday, spewing chunks of concrete into the air, spewing spoke into the street and causing windows to shatter.

MTA Chairman Joseph Lhota described the blast that occurred just before 1 p.m. at Second Avenue and 72nd Street "unacceptable." No injuries were reported.

"While I am thankful that no one was injured today, I fully understand why neighbors of the construction site are upset. I am, too,” he said in a statement.

Carole Cusa, who has lived at the corner of East 72nd and Second Ave. since 1977, said she was sitting in her kitchen when the explosion happened.

“I was thrown from my chair and I knew immediately that this wasn’t the normal blasting,” Cusa said. “There was no whistle like there normally is. I opened up my window and I stretched out to see what was going on and I saw tremendous boulders on my side of the street."

Patrick Clancy, a resident of the same building, which is across the street from where the blast took place, said that although  he’s used to the explosions, this one was more abrupt than usual. He added that his wife, however, isn't use to them and this one had her rattled.

"She thinks the building is going to come down. She's got it completely in her head that the building is going to come down on top of us," Clancy said.

MTA chief spokesman Adam Lisberg, who was at the scene Tuesday, said the agency plans to investigate the cause of the explosion.

"We're getting reports of minor damage, some broken windows, things like that," he said. "I'm not trying to minimize how that feels if it's your window, but thank God that was the only we found there was evidence of that went wrong."

No additional work will continue at that site until they know exactly what happened. There is a large crane on the lot where the explosion took place. The MTA said it was conducting an inspection to also ensure that site is safe.

The blast was helping make way for an elevator shaft for the subway line.

Emergency responders were on scene. The Department of Buildings was also at the site to assist the MTA and the FDNY and assess the situation.

(Photo: Contractors are in the process of removing the shattered windows from a shop at 72nd Street and Second Ave, and putting wood panels in the windows.Brigid Bergin/WNYC)

Brigid Bergin and the Associated Press contributed reporting