Emergency crews are investigating damage caused by a blast related to the construction of the Second Avenue subway line on the Upper East Side Tuesday afternoon.
The New York City Fire Department says it happened just before 1 p.m. in the area of 72nd Street and Second Avenue.
An MTA spokesman said the explosion was part of a series of daily "controlled" blasts performed by the MTA with the FDNY on scene.
Fire and Metropolitan Transportation Authority officials said there were no reported injuries and all of the agency's workers were accounted for.
Michael Horodniceanu, the president of MTA Capital Construction, said it's unclear how the explosion happened.
"This is an issue that has to be looked at carefully," Horodniceanu said. "It's an engineering issue. We have to understand exactly what happened. Once we know, then we'll know how to prevent that from happening in the future.
The MTA said the force of the explosion knocked off the wooden piling and steel plate covering the blast area. That allowed the debris to fly out and onto the street.
But the fire department said all necessary protocols to do the blasting were followed.
That means the road and crossing were closed to cars and people at the time of the explosion.
"There were no injuries associated with this blast," said FDNY Chief James Esposito. "We did have some collateral damage involving some windows on the adjoining structures, but it was relatively minor from what we've seen."
Buildings Department officials said six windows in a nearby building were damaged and a first-floor art gallery in that building was vacated.
DOB officials also say they inspected all the buildings and a crane surrounding the blast site and said they were not damaged.
"I looked and I saw it was total gray, and like stuff started flying and I just hit the floor because everything in the store is glass, there's nothing to duck under and I just went and hit the floor and covered my head waiting for another blast or something and I just couldn't see anything around," said one witness. "It was just total dark, with the smell of sulfur and flying debris and glass."
Some residents are calling for the blasting to stop, while others say residents need an alternative to the overcrowded Lexington Avenue line.
"Nobody got hurt," said one resident. "Maybe this will make things safer. This is New York City. Things needs to move on. Things need to happen. This is the course of doing business. There is some really hard rock underneath this island and they need to blow it up with dynamite."
The MTA has halted blasting at 72nd Street and Second Avenue but is continuing blasting elsewhere along the avenue. They say it's safe.
East 72nd Street was closed for a couple of hours but has now reopened to traffic.
MTA Chairman Joseph Lhota called the blast completely unacceptable.
In a statement, he went on to say, "I fully understand why neighbors of the construction site are upset. I am, too. The safety of the community is the MTA’s utmost priority. We will continue working with the community to ensure their concerns are heard and acted upon.”