NORTH BERWICK — The Amtrak Downeaster has resumed service through North Berwick following a deadly crash Monday morning, but Route 4 at the crash site remains closed.

Crews have been working to clean debris from the area after the Amtrak train collided with a trash hauling tractor-trailer at about 11 a.m. The collision killed the driver.

The remains of the trash trailer had been lifted onto a flatbed trailer alongside the tracks and workers were using a large hose attached to a vacuum to clean up debris.

Investigators returned to the scene today as they continue to try to piece together exactly what happened. The truck apparently locked up its brakes approaching the intersection as the railroad crossing barricades came down.

The truck slid into the intersection and was hit by the train, which typically travels 60 mph through there.

North Berwick Police Chief Stephen Peasley said this morning that it may be difficult for investigators to ever know how fast the truck was going because of the damage to the truck, which was split into four pieces, some of which burned.

However, railroad authorities have recovered a data recorder, similar to a black box on an aircraft, that should provide information about the speed of the train at the time of impact, he said.

The truck was equipped with a global positioning system which will provide some information and police are reviewing the driver’s cell phone records to explore whether that could have contributed to the crash, said Steve McCausland, spokesman for the Maine Department of Public Safety.

Patricia Quinn of the Northern New England Passenger Rail Authority said Tuesday’s 5:45 a.m. train left Portland on schedule. She said the speed through the section of track at the crash site will be 10 mph, so delays were possible.

The Associated Press contributed to this story.