One woman bought a club to keep by her door.

Another woman moved out, and a third decided she could no longer stay.

Twice last month, a man broke into apartments in separate buildings in the same block of Irving Street in Northwest Washington and sexually assaulted female tenants. For the past two weeks, residents in this Mount Pleasant neighborhood have been on edge, and on alert.

They turned to their neighborhood listserv. They got security cameras. And they got ready.

On Monday afternoon, a man broke into a ground floor apartment, two women screamed, and neighbors confronted the man.

One, then two, then three men chased the intruder, who police said sped down an alley on a stolen bicycle, threw a brick at his pursuers and threatened that he had a gun.

They kept at the chase until police got there and caught him.

D.C. Police Chief Peter Newsham credited homeowners who had surveillance cameras that captured images of the assailant in May and singled out for special praise the man who heard the screams Monday and “put himself in jeopardy to assist the police in closing this case.”

Police said the suspect was wearing the same shirt with a Levi’s logo and red shoes seen in pictures after last month’s attacks.

Newsham said detectives think the suspect, Lester Wilkerson, 58, of Southeast, is responsible for the attacks on May 21 and 23 and the home invasion Monday. In each case, police said, he kept one hand under his shirt as if he had a gun, but never displayed one. Police said they did not find a weapon.

Wilkerson was charged with three counts of burglary, two counts of sexual assault and one count of assault with a dangerous weapon. His attorney with the Public Defender Service did not return a request for comment. The suspect was ordered detained and has a hearing set for Friday in D.C. Superior Court.

Newsham described Wilkerson “as a predator” and said he has a history of arrests; court records show convictions in the District and Maryland for sexual assault and burglary dating to 1981.

He was released from prison two months ago after being convicted in 2007 of breaking into an apartment on Irving Street, across the street from the recent incidents. He pleaded guilty to kidnapping in that case and admitted to forcibly holding a woman by the neck and threatening to shoot her as two small children she was babysitting watched.

Court records show he was released from prison in April and was on supervised release in that case when police arrested him Monday.

Newsham and Mayor Muriel E. Bowser (D) announced the arrest Tuesday, on the same street where the attacks occurred. Residents who joined them expressed relief — but their anxiety remained.

The police chief noted that break-ins and violent attacks “can really rattle a community.”

The first attack occurred about 1 a.m. on May 21, when someone broke into a building by removing a rear air-conditioning unit, police said.

Police said the man confronted a woman in her bedroom, forced her to undress, demanded money and sexually assaulted her. Police said he then forced her to accompany him to knock on the door of the apartment where the building’s owner lives.

That man, Robert Fleming, 71, said the woman apologized for waking him up, then added: “ ‘But a man took money from me and he’s still here and he wants money from you.’ ”

The man “then stepped into view,” Fleming said. “He said, ‘Give me your money or I’ll kill you.’’’

Fleming turned over about $45 and police said the man left with Fleming’s bicycle.

Police said they think the same man broke into another building a few doors away two days later — this time through a rear basement window that had been left unlocked. He confronted a woman in her bedroom, demanded money and sexually assaulted her, according to police.

Then, on Monday, a woman and her adult daughter returned to their Irving Street apartment, between two buildings where the previous attacks occurred, after an afternoon of violin practice. The mother sat on the living room couch — then suddenly saw a man appear in the room. He had apparently broken a back window to get inside before the two women got home. Police said he demanded money as he held a hand under his shirt, “as if he had a weapon.”

But the woman, who along with her daughter spoke on the condition they not be identified because they are victims of a crime, said she screamed. Her daughter then came into the room, appearing to startle the man.

“I don’t think he expected that,” the woman said.

She said she then “instinctively turned around, hoping he wouldn’t shoot me dead in the back, unlocked the front door, opened it and went outside, and screamed louder than I had before.” Her daughter told the man she had no money and also fled.

A neighbor the woman had never met ran outside, found out what happened and ran through his house to the back alley to see the man leaving on a bicycle.

Fleming, who said he talked with the neighbor, said two other men joined the chase. One called police as they ran, with officers taking up the pursuit after they arrived.

Newsham noted that the neighbor continued the chase even knowing the attacker might be armed and after he had thrown a brick at him. That neighbor, Matthew J. Shannon-Browne, said in an emailed statement late Tuesday that he had to act.

“I’m not a hero, I’m a neighbor,” Shannon-Browne, 39, wrote. “I knew it wasn’t ‘The safe thing to do’ but I knew deep down in my gut that I needed to help the police stop him.”

Fleming said that when the men returned to Irving Street after the chase, neighbors gave them a round of applause. Noting the man who first rushed to the screams, Bowser said: “We are extremely grateful to him.”