EAST LYME, Conn. (AP) – A fatal accident in southeastern Connecticut forced the shutdown of a key highway in the Northeast on Friday, and transportation officials warned it might not fully reopen until early today.

The accident on southbound Interstate 95 involving a tanker, tractor-trailer and four cars happened around 10:20 a.m., police said. Three people were killed and three others were taken to area hospitals, police said.

“It’s a significant accident,” said Lt. J. Paul Vance, a state police spokesman.

State police said witnesses told them the tanker was northbound when the driver lost control and drove through the guardrail, over the median and into southbound traffic.

Officials said the tanker truck, which was carrying about 8,500 gallons of home heating oil, jackknifed and landed on its side. Firefighters sprayed foam as a precaution in a fuel spill, and state environmental officials were sent to assess cleanup needed at the site.

The interstate is the main artery that connects New York, Providence and Boston in the region. The accident site also is near the state’s two large casinos, Mohegan Sun and Foxwoods Resort Casino.

Kevin Nursick, a spokesman for Connecticut’s Department of Transportation, said its crews would assess damage to the road only after police finish.

“It’s hard to tell at this point what repairs might be needed,” he said. “We don’t want to be under foot trying to assess roadway conditions while they’re still trying to investigate this tragic accident.”

All lanes in both directions remained closed as the Friday afternoon rush hour picked up. Some or all lanes could remain closed through midnight or even into early today depending on the length of the investigation and severity of the roadway damage, he said.

Authorities also shut Interstate 395 from exit 77 south to I-95 and a portion of Route 1. State police urged drivers to avoid the area if possible. East Lyme High School canceled all after-school activities, including a play and a football game, because of traffic.

Phyllis Martino of Wallingford was en route to a job interview at Foxwoods when she saw the accident.

She told The Day of New London that the tanker truck was driving north, tailgating a minivan and swerving in and out of traffic until it hit a guardrail, lost control and crossed the median into oncoming traffic.

The tanker truck is owned by Northeast Carriers LLC, which had a satisfactory rating, the highest possible, from the Federal Motor Carrier Safety Administration.

A message seeking comment was left with Northeast Carriers.

AP-ES-11-02-07 1623EDT