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An intentional underground explosion on the Second Avenue subway project at 72nd Street propelled a thick column of debris and smoke into the air and shattered windows above ground on Tuesday.

The authorities said that no injuries had been reported as a result of the blast, around 12:45 p.m., and that work would be suspended.

“We were doing a controlled blast,” said Adam Lisberg, a Metropolitan Transportation Authority spokesman, “when clearly something went awry and an explosion was felt at street level.” Photos by a witness published by The Daily News show a violent eruption rising eight stories in the air.

Michael Horodniceanu, president of the authority’s capital construction division, said that workers had been blasting to clear space for an escalator from the street to the subway, but that “we do not know why” the blast erupted up onto the street.

Joseph J. Lhota , chairman of the transportation agency, said Tuesday: “What happened at the Second Avenue subway construction site today is completely unacceptable. The M.T.A. is investigating what went wrong and will not resume work at the 72nd Street site until we receive a full explanation for what happened.”

Six windows were damaged at 260 East 72nd Street, at the corner of Second Avenue, including at the Kolb art gallery, which was vacated and not immediately allowed to reopen, the Buildings Department said.

Lisa Tannenbaum

Just down Second Avenue from the gallery at Daisy’s Café, Venancio Arvizo, a worker at the cafe, said he was outside on his lunch break when he heard a bang and saw a cloud of dust and debris flying out of the white building on the opposite corner that houses the entrance to the dig site. “The buildings were shaking,” Mr. Arvizo said.

Suzanne Splan, who lives 16 stories above Second Avenue near the corner on 72nd, said that she heard blasts all the time, including one that knocked the clock off her wall, but that this one was a lot louder than usual and was not accompanied by the usual one-beep warning and three-beep all-clear signal the excavation crew uses before and after blasts.

“It shook very, very bad,” Ms. Splan said. “The bed really moved.”

James Esposito, an assistant fire chief, said property damage appeared to be confined to some windows and to the construction site itself on the northwest corner. He said utility crews found no damage to gas or water lines.

The $4.45 billion Second Avenue subway project has caused a series of inconveniences for residents and businesses on the Upper East Side. Last November, the transportation authority temporarily halted blasting on the site near 72nd Street after complaints about smoke and dust.

Assemblyman Micah Kellner’s district includes the blast site. He called the episode “another example of the M.T.A.’s lack of willingness to have oversight or hold their contractors accountable.”