Portland police are investigating an attack and robbery of a cab driver over the weekend.

Police said the driver picked up three men at Congress and Brown streets and drove them to Dow Street in the West End at 2:30 a.m. Saturday.

According to police, when the driver stopped to collect his fare, the man in the front passenger seat got out but the two in the back seat started hitting him. In the struggle, one of the attackers stabbed the driver very close to one of his eyes.

During the fight, the cab started rolling down Dow Street and crashed into a tractor-trailer parked on Congress Street, police said. The suspects ran and the victim was taken to the hospital for treatment, police said.