Two ferries carrying more than 150 commuters collided in the fog of Boston Harbor early Tuesday. There were no reports of serious injuries, a Coast Guard spokesman said.

The ferry boat Massachusetts, inbound from Hingham with 151 passengers and three crew members, collided with the ferry Laura, which had just four crew members on board, at about 7:30 a.m., Petty Officer Zach Zubricki said.

"We were chugging along and we just heard this big smash," said Mark Odell, 37, a passenger on the Massachusetts. "There wasn't a lot of shake up, there were a couple shrieks and screams."

He said the crew immediately started passing out life vests.

Emergency medical services met the Massachusetts at Rowe's Wharf after the collision near South Boston. One man suffered cuts on his fingers but refused medical attention, Massachusetts Bay Transportation Authority spokesman Joe Pesaturo said.

It wasn't immediately clear how fast the boats were traveling when they collided. "The fog is thick and visibility is terrible," Zubricki said.

Both ferries remained afloat after the collision, although the Massachusetts had visible damage, including a gash about 3 1/2 feet long and a broken window near its bow. The Laura had an estimated $10,000 in damage. Both boats were taken out of service, but Pesaturo did not anticipate a service interruption between Boston and Hingham.

The boats are privately owned, but contract with the Massachusetts Bay Transportation Authority for commuter services. The 101-foot Laura is owned by Boston Harbor Cruises and the 88-foot Massachusetts is owned by Massachusetts Bay Lines Inc.

Boston Harbor Cruises deferred questions to the MBTA.

Massachusetts Bay Lines issued a statement saying its crew acted quickly to ensure its passengers were safe and the vessel was secure. The company said it was cooperating with the Coast Guard and the city and state in investigating the accident.