Between 8,000 and 10,800 gallons of jet fuel is thought to have poured from the tanker.

SOUTH PORTLAND (AP) – Cleanup crews were deployed in and around the Fore River after a tanker truck overturned Monday near the entrance to the Casco Bay Bridge, spilling its cargo of flammable jet fuel.

The accident at one of the state’s busiest intersections took place shortly before 7 a.m., just as the morning commute was getting under way.

The driver of the truck, Michael McCarthy, 42, of Berwick, was transported to a Portland hospital for treatment of minor bumps and bruises. No one else was hurt in the crash.

As police scrambled to steer traffic onto alternate routes, members of several state agencies, local firefighters, Coast Guard personnel and crews from a private cleanup company confronted the environmental mess.

The cargo of jet fuel, estimated at between 8,000 and 10,800 gallons, spilled from the tanker, with most of it flowing into storm drains that fed two outfalls into the Fore River.

“It will evaporate to some extent, but it’s not as volatile as gasoline,” said David Sait, director of response services at the Department of Environmental Protection. “It will stick around for a while, and it’s toxic to marine life.”

The spill occurred at low tide, and cleanup crews prepared to set a boom to try to contain the fuel within a cove made up largely of mud flats that fill with water as the tide comes in.

“The wind is favorable, so it may hold the product in against the shore, which would be helpful,” Sait said.

The overturned truck was righted shortly before noon and crews near the scene spread sand to help recover some of the spill.

The truck, owned by Four Star Bulk Transport of Raymond, N.H., was headed from a South Portland oil terminal to Pease International Tradeport in New Hampshire, said South Portland police Sgt. Christopher Cook.

Cook said excessive speed may have caused the accident as the driver was trying to make a sharp left turn on Broadway.

The southbound lanes of the Casco Bay Bridge remained closed for most of the day, forcing traffic from Portland to be diverted onto the Veterans Bridge. Northbound traffic continued to use the bridge by taking an alternate approach.

Still, morning rush-hour traffic in both directions slowed to a crawl. For many commuters, a trip that normally took 10 or 15 minutes lengthened into an hour.

AP-ES-04-07-03 1644EDT