At least three people died and 16 others were injured when a city transit bus and a tour bus crashed early Monday in the New York City borough of Queens.

"We've had a really tragic morning here in Flushing, Queens," New York City Mayor Bill de Blasio said at a news conference with city leaders near the crash site.

One of the victims was a pedestrian heading to work who had been on the sidewalk and was found trapped underneath one of the buses, said Metropolitan Transportation Authority Chairman Joe Lhota. A passenger on the city bus and the charter bus driver also were killed.

"Hard to compare to anything I've ever seen, the sheer destruction from the impact of this collision," de Blasio said.

The crash occurred just after 6 a.m. ET when the MTA bus, operated by a 10-year veteran city bus driver, made a right-hand turn and was struck by the tour bus traveling on the same road, according to city officials. One of the buses then slammed into a building, compromising the structure's integrity, de Blasio said.

The mayor cautioned that it is still too early to know if anyone was at fault and that the cause of the crash is under investigation. But Lhota said authorities are "very concerned about the speed," noting that "the buses spun around. That requires an enormous amount of speed."

The MTA driver was taken to the hospital and was "being spoken to right now by investigators," Lhota said.

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