A seven-alarm blaze in downtown Boston has destroyed James Hook & Co., a landmark wholesale and retail seafood business on the waterfront.

The fire broke out around 3:30 a.m. Friday and quickly reached seven alarms. Three hours later, firefighters continued to pour water on the smoky wooden structure, which extends on pilings over the harbor.

Fire Department spokesman Steve MacDonald said 130 firefighters were working to contain the fire, which continued to burn in the building, particularly in rooms full of corrugated cardboard boxes used for shipping seafood. Firefighters had to battle the blaze from outside the building, after being ordered out for fear it would collapse.

Debris floated in the water and the building listed to one side at 6 a.m. Fire Chief Kevin MacCurtain said he feared the building would fall into the water. A dive team was put into the water as a precautionary measure in case a firefighter fell into the harbor, he said.

There was no report of injuries, and no immediate indication of how the fire started.

James Hook & Co. has been in business since 1925, when the Hook brothers started trucking their catch of lobsters from Maine and Canada to Boston's fish piers and selling them directly to the city's top restaurants. The business now ships 50,000 pounds of lobsters a day, according to its Web site.

One of the owners, Ed Hook, told WHDH-TV that he saw smoke on the way into the city at 4:30 a.m. and knew there was trouble.

"It's hard for me to even look at the building," said Hook, who added the business is now run by third and fourth generations of his family. "I just can't believe the condition it's in. It's devastating."

No one was in the building when the fire broke out.

"Everyone's just in shock," he said. "That's our future, that's our present and that's our past."

The Atlantic Avenue building sits in the heart of Boston's waterfront, close to the luxury Boston Harbor and Intercontinental hotels and a U.S. Coast Guard facility. It is across the street from fire department headquarters and the city's Financial District.

The blaze tangled traffic in the heavily traveled area. A portion of Atlantic Avenue, the main thoroughfare along the waterfront, was shut down and the Interstate 93 exit to Purchase Street was closed.

Meanwhile, divers were in the harbor to check the integrity of the pilings below the building to ensure the pier was safe. They also had hoses in the water, to keep fire from threatening a nearby wooden pedestrian bridge, MacDonald said.