KITTERY, Maine — As three teams of investigators attempt to piece together how a five-alarm fire began on a nuclear submarine last week, it’s still too early to determine whether the incident will affect the Portsmouth Naval Shipyard.

Firefighters from four states responded to the shipyard last Wednesday evening to help local crews fight the blaze aboard the USS Miami, which has been in dry dock since March 1 for maintenance and upgrades.

After an all-night effort, firefighters managed to extinguish the fire that occurred in the forward compartments of the Los Angeles-Class attack submarine.

After a visit to the submarine Friday, U.S. Sens. Jeanne Shaheen, D-N.H., and Susan Collins, R-Maine, stressed they would continue their efforts to protect the shipyard, which was saved after being slated to shut down following the Base Closure and Realignment Commission recommendations in 2005.

While the shipyard was able to remain open and continues to perform quality work, the threat of cutbacks and potential closure looms over military facilities and activities due to economic hardships and fiscal reductions in the Defense Department.

While Navy Spokesman Gary Hildreth confirmed the investigation was under way, it is unclear how long the process will take, whether the submarine will be repaired and how it could affect the shipyard’s reputation.

“Right now, we’re in the damage control and assessment stage,” Hildreth said.