SOUTH PORTLAND – A rush-hour crash on the Maine Turnpike involving a car and a motorcycle that left the biker critically injured may have been the result of aggressive driving, authorities said Wednesday.

Robert Boston, 51, of Saco was listed in critical condition at Maine Medical Center, where he was being treated for head injuries, chest trauma and other injuries. Boston was not wearing a helmet.

The driver of the car, Saeed Hemati, 37, of Old Orchard Beach, was shaken up but uninjured in the crash, which occurred at 5:30 p.m. Tuesday near the Maine Mall.

Statements from witnesses indicated that aggressive driving played a role in the crash, said Lt. Randall Nichols of the Maine State Police, who declined to go into details.

“It’s clear that there was some interaction between the drivers in the moments just prior to the crash,” Nichols said.

Boston’s motorcycle was demolished and Hemati’s car had damage to the left side, Nichols said. The two drivers, who did not know each other, entered the turnpike in Westbrook.