A masked gunman sparked chaos on the Brown University campus on Saturday evening after opening fire on a classroom of students preparing for a final exam, killing two people and injuring at least nine others. 

The horror shooting triggered an urgent manhunt that plunged the Providence, Rhode Island community into lockdown overnight, as terrified students were made to shelter in place for hours. 

Over 400 armed law enforcement agents including the FBI and ATF were deployed to the ongoing search, with authorities stressing that 'every minute counts' in tracking down the at-large killer. 

The shooting unfolded inside the campus' engineering building at 4:22pm local time, and hours later surveillance footage was released showing the suspect fleeing the scene after unleashing a barrage of bullets on students. 

The footage did not reveal the shooter’s face, but showed the stocky suspect fully outfitted in dark clothing and what appeared to be a bomber jacket with black boots, a beanie and gloves. 

At a press conference Saturday evening, officials said they believe the gunman was in his 30s, and may have been wearing a dark camouflage mask during the horrific episode. 

The identities of the victims have not yet been released, however Brown University President Christina Paxson said all of the victims were students at the university. Six survivors are in stable condition, one in critical condition, and one sustained minor injuries. 

During the chaotic aftermath of the shooting, officials released conflicting reports that a suspect had been arrested and a secondary attack occurred blocks away - sparking confusion before both reports were later walked back by authorities. 

The first reports of shots fired were issued at 4:22pm local time inside the Barus and Holley Engineering Building, where students had gathered to prepare for final exams. 

Police arrived minutes later and a huge law enforcement response descended on the scene, but by the time officers swept the building the suspect had escaped onto the adjacent Hope Street. 

It was during this getaway that investigators captured the chilling surveillance footage showing the suspect walking briskly away from the carnage left behind. 

Chaos overwhelmed the campus as students barricaded doors and desperately texted loved ones, with the campus issuing an emergency alert warning anyone in the area to 'RUN, HIDE, FIGHT' if they encounter the killer. 

Social media was swept with images from terrified students and faculty, showing desks, chairs and possessions pushed up against doors. 

Timothy O’Hara, the deputy Providence police chief, issued a desperate plea for answers from the public as cops released the footage, which did not show the suspect's face and offered little detail on his identity. 

'If anybody should recognize this person in any way - seen him earlier, recognize his gait - obviously, we want to know about that,' O'Hara said at a press conference. 

A strict police perimeter was maintained across an area of several miles throughout Saturday night, and anyone in the area was urged to shelter in place while the killer remained at large. 

Providence mayor Brett Smiley urged anyone with information to contact authorities, as he told reporters: 'Every minute matters. We know every minute matters.' 

Investigators have not yet recovered any weapons used in the shooting, however O'Hara said at the press conference that investigators had recovered key forensic evidence in shell casings from the scene. 

A source told the Associated Press investigators believe a handgun was used by the gunman, who fired a barrage of bullets inside a single classroom during the massacre.  

The shooting spree unfolded as the campus was in the midst of final exams, and Smiley said the gunman 'walked right into' the building because doors were left unlocked for students taking the tests.  

Soon after the shooting, horrific witness accounts surfaced from students and faculty swept up in the agonizing scenes.

Brown University student Wayne McNamara said he saw two people bleeding outside his dorm room, around a block from where the shooting was reported.

'People started running and I sprinted downstairs and back outside, took my clothes off and tried my best to stop the bleeding on the two kids by wrapping my clothes around their wounds,' he told the Boston Globe.

McNamara said one of the people shot was ‘bleeding severely,’ while the other was ‘panting and [was] shot around his shoulder.'

Sophomore Zoe Weissman, who survived the Parkland school shooting in February 2018, described her horror at being plunged back into the chaos of a shooting. 

'I think mentally, you know, I feel like I'm 12 again. This just feels exactly like how I felt in 2018,' she said while speaking on MS NOW. 'But honestly, I'm really angry. I'm really angry that this is happening to me all over again, and I'm just in shock.' 

Amid the confusion over a possible suspect in custody during the shooting, President Donald Trump quickly announced that a suspect was in custody soon after university officials did so, before the alert was soon reversed. 

'The Brown University Police reversed their previous statement — The suspect is NOT in custody,' Trump wrote on Truth Social. 

Law enforcement sources told CNN that the conflicting reports were sparked by a 'confrontation' with an individual blocks away from the campus, which resulted in gunfire.

The police source said that the connection between the second incident and the suspected shooter was found to be 'unfounded', but the 'confrontation' was the reason for conflicting reports that a suspect was in custody.