Stonington — A fire that damaged at least six boats Thursday morning at Dodson Boatyard in the borough may have been caused during the process of shrink-wrapping one of the boats, a fire official said Friday.

Fire Marshal George Brennan gave the tentative cause. He said the fire was an accident and does not appear suspicious.

He said a torch is used during the shrink-wrapping process to tighten the plastic that covers the boat. Brennan said something may have caught fire at that time.

The damage to the boats is estimated at $750,000 to $1 million, he said.

The fire at the boatyard on Water Street was reported at about 10:25 a.m. Firefighters, however, had to wait about a half hour until power was shut off, to begin to attack the blaze. The fire was under control in about an hour.

Amtrak shut off service between Kingston, R.I., and Mystic from 10:46 a.m. to 1:33 p.m., due to the fire, an Amtrak spokesman said.