A Maine state trooper shot at a man's truck as he drove toward the Canadian border and refused to stop after the trooper observed a sign on the vehicle indicating the driver had an explosive inside, police say.

The trooper first tried to stop the vehicle as it was heading north on Interstate 95 at around 10:39 a.m. Monday in Houlton, Maine, according to a statement from Maine State Police. The statement did not say why the trooper initially attempted to stop the truck.

"The vehicle continued northbound without stopping, and the Trooper observed a sign indicating that the operator had an explosive device on-board," the statement said.

The truck eventually stopped between the US and Canadian ports of entry, "where troopers commanded the driver to get out of the vehicle," police said.

The driver "maneuvered the truck towards the Canadian Port of Entry and Corporal Eric Paquette shot at the driver," according to the statement. The driver was not injured and surrendered to police.

Police identified the driver as Tony Holford, 42, from Providence, Rhode Island. Holford was taken to the Aroostook County Jail.

He was charged with aggravated reckless conduct, terrorizing and failure to stop, according to the statement. CNN was unable to determine if Holford has a lawyer at this time.

"The Office of the Maine Attorney General and the Maine State Police are collaborating with Canadian authorities to investigate the incident," says the statement.

CNN asked police and the Royal Canadian Mounted Police in New Brunswick if an explosive was found in the truck but did not immediately hear back.

Police say crime scene technicians and the Maine State Police Bomb Squad are expected to continue investigating at the scene through the night.