A "person of interest" who was detained in connection with a deadly shooting at Brown University in the US will be released shortly, local officials have said.

Providence Police Chief Col Oscar Perez said there was not enough evidence to prosecute the detained person, with Rhode Island Attorney General Peter Neronha adding the evidence "now points in a different direction".

The investigation is ongoing and authorities are searching for additional video evidence that could help them track down the suspect, the local mayor said.

Two people were killed and nine others injured after a gunman opened fire at the Ivy League university in Providence, Rhode Island on Saturday.

At a joint news conference on Sunday, Col Perez said investigators did not think the person detained was the same person identified in CCTV footage of the suspect that was released on the day of the attack. The BBC has chosen to stop naming the person who has now been released.

In the footage, the suspect can be seen walking away from the scene wearing all black clothing.

Following the release of the footage, FBI director Kash Patel had said that a person of interest was detained at a hotel in Coventry, Rhode Island in the early hours of Sunday morning based on a lead from Providence Police.

Col Perez had then confirmed that officers were not looking for anyone else and were working with prosecutors to collect evidence.

At an earlier news conference on Sunday, Providence Mayor Brett Smiley said seven people who were injured in the incident remained in a stable condition, one of them is in critical condition, and another was discharged.

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 those killed and most of the injured have not yet been released, but Brown University President Christina Paxson told reporters on Saturday that all the victims, including those killed and wounded, were students.

In an email to staff on Sunday, the head of Durham Academy, a private school in North Carolina, said one of their alumna, Kendall Turner, was injured in the attack, US media reported.

"Our thoughts and prayers are with Kendall, her family, and all members of the Brown University community during this incredibly difficult time," said Michael Ulku-Steiner.

In a statement released by the university on Sunday, Prof Paxson said some areas of campus were still restricted as police continued their investigations.

Around 2,000 students were relocated to safe locations overnight, she said, adding that she was "deeply moved" by students and locals who opened up their homes.

Prof Paxson said the families of the two students killed were being supported.

"There are not enough words of comfort for families who lose a child, but we will do all we can," she added.

Smiley said an order for residents to shelter was lifted on Sunday.

The mayor said he had met with victims and their families in the hospital and was "overwhelmed" by their "courage, hope, and gratitude".

A vigil will be held on Sunday evening for the community.

Speaking at the White House, President Donald Trump said he hoped the nine injured students "get well fast" and paid respects to the families of the two people who died.

The attack on the Ivy League university brings the number of mass shootings to 389 in the US for this year, according to the Gun Violence Archive.

It defines mass shootings as having four or more victims killed or injured, not including the attacker. (BBC)

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