A Boston man is in custody after he allegedly opened fire on a busy Massachusetts road, shooting two people and leaving others fleeing for cover in the middle of the day.

On May 11 shortly after 1 p.m. local time, Tyler Brown, 46, allegedly began "firing erratically" at cars and other passersby on Memorial Drive in Cambridge, Middlesex County District Attorney Marian Ryan said at a news conference.

Brown allegedly shot two men in separate vehicles, firing upwards of 60 rounds within "a very short period of time." The two victims are being treated at area hospitals with life-threatening injuries, Ryan said.

The suspect was confronted by a Massachusetts State Police officer and a former Marine licensed to carry a firearm who each fired at Brown, striking him multiple times. He was treated on scene before being transferred to a Boston hospital, where he is being treated for gunshot wounds.

Brown is in custody at the hospital and is expected to be charged with two counts of armed assault with intent to murder and firearms offenses, per Ryan.