Two people were critically wounded Monday afternoon after a gunman armed with an assault-style rifle opened fire on traffic along a busy roadway in Cambridge, according to authorities.

Officials identified the suspect as 46-year-old Tyler Brown of Boston. Prosecutors said Brown was taken into custody following an exchange of gunfire with law enforcement and an armed civilian who intervened during the attack.

According to Middlesex District Attorney Marian Ryan, the violence unfolded near the River Street Bridge along Memorial Drive, a heavily traveled roadway beside the Charles River and close to both Harvard University and Massachusetts Institute of Technology. Harvard later confirmed there was no ongoing threat to campus.

Authorities said the suspect began firing indiscriminately into passing vehicles, creating panic as drivers and passengers abandoned their cars and ran for safety. During the chaos, a Massachusetts state trooper and a civilian identified only as a former Marine legally licensed to carry a firearm confronted the shooter and exchanged gunfire with him. Officials credited their actions with helping stop the attack within minutes.

Two men traveling in separate vehicles were struck by gunfire and remain hospitalized with life-threatening injuries. Authorities also confirmed that a state police cruiser was hit during the shooting.

Investigators said the suspect fired as many as 60 rounds in just a few minutes, damaging at least a dozen vehicles. Witnesses described scenes of terror as people hid beneath cars or fled the roadway while shots rang out.

Video footage aired by local media appeared to show the suspect carrying the rifle openly while pointing and waving the weapon in multiple directions along the street.

Authorities have not yet identified a motive for the shooting and said there is currently no indication the suspect knew any of the victims.

District Attorney Ryan described the firearm as an assault-style rifle capable of causing catastrophic harm across a wide area, noting the incident could have resulted in significantly greater casualties due to the crowded location and heavy traffic.

Brown was hospitalized with gunshot wounds suffered during the confrontation and is expected to face multiple charges, including two counts of armed assault with intent to murder, officials said.

Law enforcement agencies continue investigating the incident as officials review evidence, witness accounts, and video footage from the scene.