SOUTH PORTLAND, Maine — A truck carrying home heating oil rolled over on Interstate 295 north, spilling its cargo along the roadway and into the Fore River, authorities said.

The crash occurred about 11:30 a.m. near Exit 4. The ramp was closed and northbound traffic was down to one lane, state police said.

A majority of the spill was contained before it reached the water, a Coast Guard spokesman said, adding that “there’s only evidence of light sheening” in the river.

“An unknown amount entered into the river and an unknown amount has been recovered. What did enter was deemed unrecoverable,” said Coast Guard Lt. David Bourbeau.

The Department of Environmental Protection and Coast Guard pollution responders are on site along with other emergency personnel.

Drivers should expect significant delays both north and southbound.

Watch for updates.

CBS 13 contributed to this report.