NEW YORK (CBSNewYork) – A manhole cover tore through the floor of an MTA bus, injuring a rider Tuesday in the Bronx.

The incident took place on a BX 11 bus at around noon at 170th Street and Inwood Avenue in the Mount Eden section.

This manhole cover tore through the bottom of an MTA bus in the Bronx on Aug. 4, 2015. (credit: Image via CBS2)

This manhole cover tore through the bottom of an MTA bus in the Bronx on Aug. 4, 2015. (credit: Image via CBS2)

The passenger suffered minor injuries caused by fragments of the flooring.

A representative of the Transport Workers Union told CBS2 the driver heard a loud bang and then heard a passenger screaming.

“It sounded like an explosion. He heard the lady scream and that’s what made him apply the brake and go back there and see what the situation was,” Frank Austin, the TWU’s safety director for bus drivers, told 1010 WINS.

As CBS2’s Steve Langford reported, the sound could be heard up and down the street.

“Boom, and all I seen the bus stopped, and I see fire shooting up and people started running down the street,” Michael Parfer said.

Parker thought it was a bomb, until he saw the manhole cover fly.

“Spinned up like a spinning top, shot up through the bus. Straight up through the bus,” he said.

One witness said he noticed that the manhole cover was loose in recent days.

“The thing is like that,” he said.

The manhole belongs to the city’s Department of Environmental Protection, which had no record of a problem with the manhole involved in the incident and found no gas readings at the location.

The agency says the bus likely rolled over the manhole cover, dislodging it and shooting it into the bus.

“Heavy vehicles can sometimes damage manhole castings and that could lead to a cover being dislodged,” the DEP said.

Austin said he doesn’t buy the explanation.

“Buses go over manhole covers throughout the entire five boroughs and none have ever shot up and went through the floor of a bus,” he said. “It’s the first time I ever saw that.”

The MTA said it’s fortunate and thankful that no one was seriously injured.

The injured rider was treated for minor injuries at the hospital and released.

The bus driver was given the rest of the day off.