BOSTON (AP) — Boston's police commissioner says a 34-year-old homeless man with a violent history has been arrested in the stabbings of two city park rangers on Boston Common, the nation's oldest public park.

Commissioner William Evans said Tuesday night that a 46-year-old ranger sergeant is in surgery at Massachusetts General Hospital with life-threatening injuries. He said a 23-year-old ranger new to the service is in stable condition at Tufts Medical Center with less serious wounds.

Evans said Bodio Hutchinson attacked the unarmed rangers in what the commissioner said was an unprovoked confrontation at about 4:30 p.m. Evans said witnesses followed the suspect and provided cellphone video to police. He said a knife police believe was used in the attack was recovered from Frog Pond.

Evans said Hutchison faces attempted murder charges.