WASHINGTON — A gunman suspected of stalking homeless people asleep on the streets of New York City and Washington, D.C., killing at least two people and wounding three others, was arrested early Tuesday, police said.

Law enforcement arrested the man in Washington, and he was being interviewed, the Metropolitan Police Department said on Twitter.

The man was identified as 30-year-old Gerald Brevard, a law enforcement official told the Associated Press. Mr. Brevard, who lives in the Washington area, has a criminal history that includes an assault arrest, the official said. He was in custody Tuesday and couldn’t be reached for comment. The official was not authorized to publicly discuss the investigation and spoke to the AP on the condition of anonymity.

Police in the two cities earlier released multiple surveillance photographs, including a closeup clearly showing the suspect’s face, and urged people who might know him to come forward.

Mayor Adams and the mayor of D.C., Muriel Bowser, credited the swift coordination between the two police departments and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives. It was ATF agents who took Mr. Brevard into custody before handing him over to the MPD, according to the ATF’s Twitter feed.

“We said that the work to remove this man from our streets was urgent, and our communities responded,” Ms. Bowser said in a joint statement with Mr. Adams on Tuesday. “We know that this experience has been especially scary for our residents experiencing homelessness. Our work continues to end homelessness and ensure all residents have access to safe and affordable housing.”

Ms. Bowser and Mr. Adams held a joint news conference Monday evening to appeal for public assistance in identifying the attacker.

“This man targeted those experiencing homelessness with no regard for life, but this criminal is now off the streets,” Mr. Adams said Tuesday. “Gun violence against anyone, let alone our most vulnerable populations, is sick, but thanks to the coordination between different levels of law enforcement and the public’s help, those experiencing homelessness can breathe a sigh of relief today.”

Advocates for the homeless found comfort in the arrest but urged officials in both cities, which have significant populations of people without permanent shelter, to provide more assistance.

“The urgency of helping people move in off the streets must remain, because this is only the latest example of the risks faced by people without housing,” the policy director for the Coalition for the Homeless in New York, Jacquelyn Simone, said. “It’s not the first time that people have been the victims of violence or even homicides because of their housing status.”

Investigators in the two cities began to suspect a link between the shootings on Sunday after a Metropolitan Police Department homicide captain, a former New York City resident, saw surveillance photos that had been released on Saturday night by the New York Police Department while scrolling through social media.

The man in those photos looked similar to the one being sought by the MPD homicide captain’s own department.

The D.C. police chief, Robert Contee, credited the coordination between the departments, saying that without that officer making the connection, “It could have been months” before the link between the attacks was discovered.

The earliest known shooting happened at around 4 a.m. on March 3 in Washington, police said, when a man was wounded in the city’s Northeast section. A second man was wounded on March 8, just before 1:30 a.m.

At 3 a.m. the next day, police and firefighters found a dead man inside a burning tent. He initially was thought to have suffered fatal burns, but an autopsy revealed that he had died of multiple stab and gunshot wounds.

The killer then traveled north to New York City, police said.  

At 4:30 a.m. on Saturday, a 38-year-old man sleeping on the street in Manhattan not far from the entrance to the Holland Tunnel was shot in his right arm as he slept. The victim screamed, and the gunman fled, police said.

About 90 minutes later, the gunman fatally shot another man in SoHo, police said.

“He looked around,” Mr. Adams said. “He made sure no one was there. And he intentionally took the life of an innocent person.”

The man’s body was found in his sleeping bag just before 5 p.m. Saturday. He had been shot in the head and neck, a spokesperson for the New York City medical examiner’s office, Julie Bolcer, said. He has not been officially identified, but he was known among others who live on the streets, Ms. Bolcer said.

The victim lay in the street for hours before authorities were summoned.

“We don’t know at this point who this is whether or not they might have family who might might claim their body,” the chief executive officer of the Bowery Mission, James Winans, said. The organization takes in scores of the city’s homeless every night and is located just blocks from where the man’s body was recovered.

“Any one of us who’s homeless could have went to that same situation,” a homeless New York resident, Kess Abraham, said. 

Mr. Abraham, who became homeless last month, said he was “pained” to learn of “a guy who lived on the streets who probably was minding his own business getting murdered for no reason.”

The latest attacks were reminiscent of the beating deaths of four homeless men as they slept on the streets in New York’s Chinatown in the fall of 2019. Another homeless man, Randy Santos, has pleaded not guilty to murder charges in those attacks.

A year ago, four people were stabbed in New York City, two fatally, by a man who randomly attacked homeless people in the subway system. That assailant, who also was homeless, is awaiting trial.