BOSTON — A commuter ferry ran aground in fog in Boston Harbor on Friday, injuring four people on board.

The captain of the MV Lightning was forced to take evasive action to avoid a collision after being “cut off” by a sport fishing boat, said Joe Pesaturo, a spokesman for the Massachusetts Bay Transportation Authority.

The ferry, which was traveling to Boston from Hull with 84 passengers and crew members, struck some rocks and ran aground in about five feet of water near Long Island, one of several islands in the harbor, at about 7:45 a.m.

Conditions at the time included heavy fog and low tide, officials said.

A Boston Police marine unit monitors the safe transfer of passengers from the grounded ferry Lightning to the ferry Sanctuary in Boston Harbor on Friday. (Coast Guard)
A Boston Police marine unit monitors the safe transfer of passengers from the grounded ferry Lightning to the ferry Sanctuary in Boston Harbor on Friday. (Coast Guard)

The U.S. Coast Guard said the four people who were hurt were taken off the ferry and brought to the Black Falcon Terminal in Boston, where they were then transported to hospitals in the city.

There was no immediate word on their conditions.

David Procopio, a spokesman for the Massachusetts State Police, said one person suffered injuries that were potentially serious.

One passenger, Dieckmann Cogill, said she was on the top deck of the ferry having coffee when the captain started blowing the horn repeatedly.

"We turned and saw Long Island. We saw that we were too close . . . we knew we were going to run aground, but there was nothing we could do," Cogill told The Boston Globe.

Cogill fell forward when the ferry hit the rocks.

“My friend Kiley caught me like a football,” she said.

Coast Guard Station Point Allerton crew members respond to the grounding of the ferry Lightning in Boston Harbor on Friday. (Coast Guard)
Coast Guard Station Point Allerton crew members respond to the grounding of the ferry Lightning in Boston Harbor on Friday. (Coast Guard)

Passengers were taken off the ferry and placed on other vessels to complete their trip into Boston. The Coast Guard says the vessel was eventually able to get underway on its own power and was brought to a dock in Charlestown.

The ferry sustained damage to the hull above the water line, but no sea water got into the vessel, according to Pesaturo.

“We are offering our full support and cooperation to the United States Coast Guard, which is leading the investigation into the incident,” said Steve Poftak, the MBTA’s general manager, in a statement.

“We are also conducting an independent assessment of the damage to the vessel.”