Authorities knocked on doors and scoured yards Monday in Providence, R.I., in search of any video or other evidence that might lead them to the Brown University gunman, whose face was covered or not visible in footage captured before and after the weekend attack that killed two students and wounded nine others.

Officials released three new videos of the man they believe carried out Saturday’s attack that show him wearing a mask and a dark two-tone jacket. Although his face wasn’t visible, the footage from about two hours before the shooting provided the clearest images yet of the suspect.

The FBI said the man is about five foot eight inches tall, with a stocky build. The agency offered a $50,000 US reward for information leading to the identification, arrest and conviction of the person responsible.

“We want to identify the individual and bring them to justice,” Providence’s police chief, Col. Oscar Perez, said at a news conference, urging people who might recognize the suspect to call a tip line.

Police renewed their search after releasing a person of interest Sunday once they determined the evidence pointed elsewhere. Meanwhile, details began to emerge about the students who were shot.

WATCH | For some, Brown University attack wasn’t the first school shooting:

2 killed in shooting at Brown University

A person of interest was arrested and later released following a shooting at Brown University that killed two people and injured nine others and resulted in a 12-hour campus lockdown. For some of the witnesses, it wasn’t the first school shooting they’d experienced.

The lockdown order for the Ivy League school was lifted Sunday after authorities said they’d detained a person of interest in the attack. But hopes for a quick resolution were dashed when they announced hours later that they had released him.

Questions swirl about campus security

The abrupt change of direction marked a setback in the investigation as questions swirl about campus security, the apparent lack of school video evidence and whether the focus on the person of interest gave the attacker more time to escape.

Colin Moussette, who has friends at Brown and is considering enrolling next fall, said while visiting the campus Monday that he felt uneasy knowing the suspect hadn’t been caught.

“How someone got away, like, in the middle of the day is, to me, not only heartbreaking but very concerning,” he said. “How they got access to the building is concerning.”

WATCH | Search continues for Brown University shooter:

Manhunt for Brown University shooter continues

Two victims have been named in the shooting as the hunt for the gunman continues. CBC speaks with a Brown University student about the attack and with reporter Willy Lowry.

Before Monday’s news conference, police released a second video showing someone dressed in all black walking along a city street minutes after the shooting. The video — like an earlier one released the day of the shooting — didn’t show the suspect’s face.

In a neighbourhood near the university, a line of officers scraped their feet through a snow-covered yard looking for evidence. Meanwhile, agents identifying themselves as U.S. marshals asked locals if they had security cameras.

State Attorney General Peter Neronha, who said Sunday that there weren’t many cameras where the attack happened, said Monday that investigators were “making steady progress.”

Law enforcement on Monday appeared to still be performing the most basic of investigative tasks: tracing the suspect’s movements in the minutes after the attack and searching for physical evidence near the crime scene.

“I was really glad to see that they were doing something,” said Katherine Baima, who lives in the area. “This is the first time any of us in my building, as far as I know, had heard from anyone. We hadn’t gotten alerts and we were really surprised that there hadn’t been anyone searching, let alone knocking on doors, on the first night.”

Four young people are shown holding candles at a night vigil.Attendees hold candles and listen to local artists sing during a vigil at Lippitt Memorial Park on Sunday, a day after Brown University was locked down amid reports of a shooting on its campus in Providence. (Taylor Coester/Reuters)

The shooting happened in an auditorium-style classroom where students in a study group were preparing for an upcoming exam.

Ella Cook, 19, a sophomore who was vice-president of the Brown College Republicans and beloved in her church in Birmingham, Ala., was one of the students killed, according to her pastor at home.

In announcing her death Sunday, the Rev. R. Craig Smalley described Cook as “an incredible grounded, faithful, bright light” who encouraged and “lifted up those around her.”

“Ella was known for her bold, brave, and kind heart as she served her chapter and her fellow classmates,” Martin Bertao, the president of the club, said in a message posted on X.

WATCH | Officers searching for suspect, mayor said Saturday:

At least 2 killed, 8 injured in Brown University shooting: Providence, R.I., mayor

Providence, R.I., Mayor Brett Smiley said police are still looking for a suspect behind a deadly shooting at Brown University’s engineering building Saturday afternoon.

The other student who was killed was Mukhammad Aziz Umurzokov, 18, a freshman majoring in biochemistry and neuroscience. He was helping a friend at a review session for an economics final when he was fatally shot, his sister said.

As a child, Umurzokov suffered a neurological condition that required surgery, and he later wore a back brace because of scoliosis, said Samira Umurzokova, noting that the family immigrated to the U.S. from Uzbekistan when she, her brother and sister were young.

“He had so many hardships in his life, and he got into this amazing school and tried so hard to follow through with the promise he made when he was seven years old,” she told the AP by phone Monday.

Only one of the nine people wounded had been released as of Sunday, Brown president Christina Paxson said. One was in critical condition and the other seven were in critical but stable condition. Providence Mayor Brett Smiley said Monday evening that none of their conditions had degraded, but that he didn’t have further information.

Durham Academy, a private K-12 school in Durham, N.C., confirmed that a recent graduate, Kendall Turner, was critically wounded and that her parents were with her.

“Our school community is rallying around Kendall, her classmates and her loved ones,” the school said in a statement.

Another wounded student, freshman Spencer Yang, 18, of New York City, told the New York Times and the Brown Daily Herald from a hospital bed that there was a mad scramble after the gunman entered the room where he and the other students were studying for finals. Many students ran toward the front of the room, but Yang said he wound up on the ground between some seats and was shot in the leg.

Yang, who expects to be discharged in the coming days, said he tried to keep some of the more seriously wounded students conscious until police arrived.

Brown was no longer on lockdown and the city’s schools were open Monday. But some colleges and universities, including in Rhode Island and some Ivy League schools, were increasing security in light of the attack. Yale said extra security would be in place for Hanukkah celebrations.

A street sign shows a thank you message to first respondersA sign thanking first responders stands in a neighbourhood near Brown University the day after a shooting on the school’s campus. (Steven Senne/The Associated Press)

The shooting occurred as final exams were underway at Brown, one of the nation’s oldest and most prestigious schools.

Investigators were not immediately sure how the shooter got inside the first-floor classroom.

The attack set off hours of chaos on campus and in the surrounding neighbourhoods, as hundreds of officers searched for the shooter.

Li Ding, a Rhode Island School of Design student who is on a dance team at Brown, was upset that there wasn’t better security on campus.

“The fact that we’re in such a surveillance state but that wasn’t used correctly at all is just so deeply frustrating,” Ding said.

People dressed in winter gear gather in front of a large fence on a university campus.People gather near a makeshift memorial Monday on the campus of Brown University, not far from the scene of the weekend shooting in Providence, R.I. (Robert F. Bukaty/The Associated Press)