A person of interest has been detained in connection with a US shooting at Brown University that left two people dead, police said.

Nine others were injured when a gunman opened fire at the university in Providence on Saturday.

Police confirmed on Sunday that a person had been detained, and an earlier order for people on the Brown campus and surrounding areas to shelter had been lifted.

Of those injured, medics reported that one person was in critical condition, six were 'critical but stable,' and two others sustained less severe injuries.

The gunman opened fire in a classroom at around 16:00 local time (21:00 GMT) on Saturday at the Holley engineering building at the eastern end of Brown's campus, according to officials.

The identities of the deceased and injured victims have yet to be released, but Brown University President Christina Paxson stated during a press briefing on Saturday that all victims involved were students.

Earlier, police released CCTV footage capturing a male suspect walking away from the scene dressed in all black clothing. However, officers reported that no firearm was found during a thorough sweep of the building.