KITTERY — Officials have started ventilating fresh air into a nuclear-powered submarine two days after a fire swept through part of the vessel at the Portsmouth Naval Shipyard in Maine.

Investigators hoped to enter the USS Miami later Friday.

The Navy is sending three teams of investigators to sort out what happened. The fire Wednesday heavily damaged some forward compartments, including living quarters, command and control, and the torpedo room. The submarine’s nuclear propulsion was spared.

U.S. Sens. Susan Collins of Maine and Jeanne Shaheen of New Hampshire visited the shipyard. They were told it was too early to say whether the Miami was beyond being saved.

Paul O’Connor, president of the Metal Trades Council, said his union is concerned about the possible loss of work is the submarine is scrapped.