An off-duty Laurel police officer was critically injured last night when he was stabbed repeatedly during a traffic dispute off Interstate 70 near the Carroll County line, officials said. A suspect was arrested by Howard County police.

The off-duty officer, Joseph Thomas Jr., 30, was listed in critical but stable condition in the shock trauma unit of the University of Maryland Hospital in Baltimore, said Sgt. Gary Gardner of the Howard County Police Department. Thomas had multiple stab wounds in the back, Gardner said.

Police arrested a man identified as Ronald David Thomas, 33, of Union Bridge, Md., in connection with the assault, though no formal charges had been brought against him last night, Gardner said.

The incident occurred about 8 p.m. on the westbound lanes of Interstate 70, Gardner said. Joseph Thomas was on his motorcycle when he became involved in a traffic dispute with the driver of a pickup truck, Gardner said.

Thomas and the driver of the truck both pulled over to the right side of the interstate, where a fight ensued. Thomas was stabbed during the fight, Gardner said. The driver of the pickup allegedly ran to a house about a half-mile away and asked to use a telephone, Gardner said. The family in that home called paramedics and police, who arrived to find the driver of the pickup still at the home, Gardner said. The suspect was treated at Howard County General Hospital for cuts, Gardner said.