PORTLAND — A 49-year-old woman who was shot Sunday outside an apartment building in Portland’s Bayside neighborhood is expected to recover, but the man who shot her remained at large Sunday night. A neighbor said the woman was shot in the knee.

Portland police spokesman Lt. Robert Martin said the woman and her attacker were arguing on a sidewalk in the vicinity of 19 Parris St. when he shot her at 8:44 a.m. The victim’s name is not being released.

In a statement, Martin described the assailant as a “younger white male” who was armed with a silver semi-automatic handgun. He was driving a silver sport utility vehicle with a Massachusetts license plate starting with the numbers 771.

Martin said there was a white male passenger in the front seat of the SUV. After he shot the woman, the man was last seen driving toward Portland Street.

The Bayside neighborhood has a cluster of social service agencies, such as the Preble Street Resource Center and the Oxford Streeet Shelter, which attract large numbers of homeless and drug-addicted people on a daily basis.

In this past weekend’s edition, the Maine Sunday Telegram provided a graphic and disturbing look at the area. It’s not uncommon for residents to see drug use, fights and even sexual acts in public places, and the activities have pushed some of them to the edge of their tolerance.

“It used to feel like it was a coexistence, but now I feel violated,” Sarah Michniewicz, who has lived on Cedar Street near the city shelter for 20 years, told the newspaper. “I can’t walk into my backyard without wondering what I will find.”

Police were not saying what provoked the argument and violence Sunday morning. In an email Sunday evening, Martin said he would not be able to comment further because of the ongoing investigation by police detectives.

But Laura Cannon, a Parris Street resident, said the shooting may have been drug-related. The shooting happened on a sidewalk near her home.

Cannon said she and her husband went outside to investigate and overheard the victim, whom she did not recognize, telling police that she had confronted her assailant about doing drugs on a public way. Cannon said the woman told officers that the man and his friend were smoking crack cocaine.

“The guy said (expletive) and shot her in the knee,” said Cannon, who is vice president of the Bayside Neighborhood Association.

“She had been shot in the knee and was sitting on the sidewalk and bleeding,” said Cannon, who has lived in the neighborhood since 2010.

Cannon said that in the past, she herself has confronted people doing drugs on the street, but plans to be more cautious in the future considering what happened Sunday.

Parris Street was shut down for several hours by police investigating the shooting. Motorists who had parked on the street were not allowed to move their vehicles while police investigated.

Anyone with information about the crime is being urged to contact the Portland Police Department at 874-8575.

Police on the scene of a shooting on Parris Street in Portland on Sunday morning. (Carl D. Walsh/Portland Press Herald)