Investigation underway after shooting on Memorial Drive in Cambridge

Investigators in Cambridge are working to learn why a gunman went on a rampage on Memorial Drive Monday, opening fire on officers, people, and vehicles before beign stopped by police.

The alleged gunman, Tyler Brown, 46, of Boston, remained in police custody Tuesday morning in the hospital being treated for gunshot wounds; two people shot by the suspect are also hospitalized.

12 cars were riddled with bullets and towed from the scene while investigators spetn ours on the scene tracking down surveillance video from nearby homes and businesses.

Cell phone video captured the terrifying sights and sounds of an active shooter opening fire with an assault-style rifle on cars traveling along Memorial Drive. The shooting came shortly after Boston police alerted Cambridge polcie that the suspect had been acting erratically earlier and may be armed.

The district attorney said a state trooper and Marine veteran who has a license to carry a weapon ran toward the gunman, identified as Brown, who was under the supervision of probation or parole.

The suspect and two men who were hit by gunfire while driving their cars, including one who was behind the wheel of an MBTA rideshare van, were all rushed to neary hospitals. The two drivers are facing critical injuries.

Investigators said about 60 shots were fired.

The DA said that office is interviewing hundreds of witnesses and asked that anyone in the area who saw or has video of the shooting come forward.