A 54-year-old Arlington County man, described by authorities as “a good Samaritan,” died after being beaten Thursday night after he got out of his vehicle to help a woman who was being sexually assaulted on a street, law enforcement officials said.

The man who died, Patricio Salazar, was driving in the 1300 block of South George Mason Drive shortly before 9:30 p.m. when he saw a woman in her early 20s being assaulted by a man, according to one official, who spoke on the condition of anonymity because the killing is still being investigated.

After Salazar stopped his vehicle and went to help the woman, the official said, the woman’s assailant beat Salazar and left him in the street unconscious. He was pronounced dead at a hospital.

The suspect, identified as Michael Nash, 27, fled, Arlington police said. They said he later tried to rob two people of a cellphone. When those victims fought back, police said, Nash fled again. Police said he later robbed a woman of her cellphone, after which officers caught him near Columbia Pike and George Mason Drive.

The law enforcement official said “there was some relationship” between Nash and the woman and that the two had been walking together. The official said Nash and Salazar did not know each other.

Nash has been jailed on charges including forcible sodomy and abduction with the intent to defile, according to police. He is being held without bond at the Arlington jail. Police said other charges are pending, including those related to Salazar’s death, which is being treated as a homicide.

Michael Nash, 27, was arrested and charged in connection with Thursday night’s incident. (Arlington County Police Department)

The D.C. region has seen more than 220 homicides so far this year, according to tracking by The Washington Post.

Paul Duggan contributed to this report.