Investigators knocked on doors, combed through bushes and released more video and photos as they hunt for a masked gunman who opened fire at Brown University over the weekend, killing two students and wounding nine others.

“It’s all hands on deck,” Providence police chief Col. Oscar L. Perez Jr. told reporters Monday evening.

“We’re at the 49th hour, and there’s no one that wants to put this individual in handcuffs more than us,” he went on.

The investigation suffered a setback Sunday when authorities determined that ballistics evidence pointed to someone other than the person they had previously detained as the gunman in the deadly campus shooting.

Law enforcement is pleading with the public to help in their search, releasing additional images, requesting any new details or observations and offering a reward.

New videos of the suspected gunman shared Monday show a man in dark clothing walking in the vicinity of Hope Street between Manning and Benevolent streets.

He wore a beanie and mask that obscured most of his face except for his eyes. In one video, he appeared to stroll casually with one hand tucked inside his pants pocket.

The FBI described him as having a stocky build and said he is about 5 feet, 8 inches tall. Officials believe the person responsible was a lone shooter.

In a post to social media, Brown University officials encouraged students who were in the building where the shooting occurred to contact local police.

“Even an incidental detail may be helpful,” the post read in part.

‘Everybody is scared’

Sophomore Jacklyn McLeary, who remained on campus after the shooting, said she has spent the last 48 hours inside with friends.

“Everybody is scared,” she said. “We’ve been watching the news, and we’ve been trying to see if there’s any updates. And the fact that there’s still not anybody has really made us not want to do anything.”

“There’s definitely a bit of frustration and a lot of fear,” she added.

During a sometimes heated news conference Monday, FBI officials announced a $50,000 reward for information leading to the identification, arrest and conviction of the gunman.

Investigators addressed pointed questions about why a person of interest had been announced Sunday only to be released hours later.

The mayor and other leaders stressed their commitment to the investigation and finding the gunman.

“We’ve all been working for now 49 hours. We’re tired. We’re serious about the task at hand,” Mayor Brett Smiley said. “I know that people are weary, and so I’m asking please for a little bit of patience and grace.”

Investigators said Monday that the shooter “definitely targeted Brown University,” but they continue to hunt for a motive, police chief Perez said. When asked whether the shooter yelled something during the attack, Perez said, “that’s something we’re investigating.

“We took statements, and we have to confirm,” he told reporters.

Providence officials said there appears to be no threat to public safety or to the city. Still, an enhanced police presence was visible on campus and throughout Providence on Monday.

Security questions

The renewed manhunt comes as members of the Brown community ask questions about campus safety and communications before and after the deadly rampage at Barus & Holley, an engineering and physics building.

On Sunday, Rhode Island Attorney General Peter Neronha said there was a lack of surveillance cameras near the unlocked classroom where the attack unfolded. Inside, students studied for upcoming final exams and ducked for cover or barricaded themselves in using furniture when shots rang out.

Investigators have said they do not know how the shooter got inside the first-floor classroom.

“I’m hopeful that the security, the cameras, everything about like the campus will feel safer,” said Brown University student Hudson Nguyen.A comparison between one of the guns found on the person of interest, who was detained but has been released, and the ballistics recovered at the scene of the shooting did not match, two senior law enforcement officials briefed on the matter previously told NBC News.

Zoe Weissman, 20, one of at least two Brown students who has experienced multiple school shootings, said she feels safe returning to campus next semester. She attended Westglades Middle School, adjacent to Marjory Stoneman Douglas High School in Parkland, Florida, when a former student opened fire, killing 17, in 2018.

“In reality, if someone has a gun, there’s not much that’s going to stop them, and that’s why the issue lies with the guns, not with the security itself,” she said, adding that she hopes Brown adds additional security cameras and swiping for buildings.

“But really, I hope that they don’t take the stance of going full surveillance state and turning the school into a prison,” she said. “I don’t think that would help anyone.”