Police in Providence, Rhode Island, on Tuesday released a new image of a person of interest in the deadly shooting at Brown University as the investigation entered the fourth day.

More images or videos are expected to be released later Tuesday, the Providence Police Department said on social media, urging anyone with information to contact the FBI tip line online or at 401-272-3121.

"Even small details may be critical to this," police said.

The latest image, though blurry, was the clearest picture of the person of interest released so far. The FBI said the man is about 5 feet, 8 inches tall, with a stocky build. The bureau has offered a $50,000 reward for information leading to the identification, arrest and conviction of the gunman.

The search for the shooter who killed two Brown University students and wounded nine others on campus on Saturday continued Tuesday. Two of the nine injured victims have been released from the hospital, while five are in critical stable condition, one is in critical condition, and one is stable, according to Rhode Island Hospital.

The students killed in the attack were identified as Ella Cook, a sophomore from Alabama, and Mukhammad Aziz Umurzokov, an Uzbek American freshman student.

"Both were brilliant and beloved — as members of our campus community, but even more by their friends and families," Brown's president, Christina H. Paxson, wrote in a letter Tuesday to the university community. "Our hearts continue to be with them in their profound sorrow."

Investigators say they are looking to interview anyone who was in the area of the shooting. They're also continuing to search for the area and find more videos for evidence that might lead to the gunman.

Meanwhile, Brown University says it has seen an increase in swatting calls since the shooting. The community has seen increased security presence, with restriction to buildings and areas, but students say it will take effort and time for them to feel safe.

"We were in a state where Brown felt incredibly safe, and that bubble of safeness was completely popped when we were violated by a shooter entering our campus," Talia Levine, a senior at Brown University who barricaded for four hours during the shooting, told CBS News.