Driver towing trailer killed when truck goes off I-95 bridge over Patapsco River on May 5.

A driver was killed after his pick-up truck went off a bridge carrying Interstate 95 over the Patapsco River between Baltimore and Howard counties Monday, according to the Howard County Department of Fire & Rescue.

Emergency responders were dispatched to River Road in Howard County, below the bridge, about 11:45 a.m. They located the driver, who was pronounced dead, said Maria Hogg, a department spokeswoman.

The driver has not been publicly identified.

Maryland State Police are leading the investigation into the accident. Based on preliminary evidence, they determined a 2005 Ford truck towing a trailer was traveling south on I-95 when the truck and trailer separated for an unknown reason, police said.

The truck then struck the wall on the right side of the bridge and went over it. The truck landed in the Patapsco Valley State Park below, police said, while the trailer remained on I-95.

In the park, the truck became engulfed in flames, police said. The driver's body has been sent to the chief medical examiner's office in Baltimore for identification.

Sgt. Marc Black, a state police spokesman, said police would release more information about the driver pending the notification of next of kin. The cause of the truck going off the bridge remains under investigation, he said.

The accident closed two lanes of southbound I-95 for several hours. It also closed River Road.

Engineers with the State Highway Administration responded to the scene, assessed the bridge and made "necessary repairs," police said.