The man believed to be behind a mass shooting at Brown University that left two people dead and wounded several others has been found dead, officials announced Thursday.

Officials also believe the same man, a 48-year-old Portuguese national who was a student at Brown, was responsible for the fatal shooting of a physicist at the Massachusetts Institute of Technology in his Boston home.

Providence police chief Oscar Perez, who identified the suspect as Claudio Neves-Valente, told reporters: "He took his own life tonight."

The shooter, who was found at a storage unit in New Hampshire along with two firearms, is believed to have acted alone.

"Tonight, our Providence neighbors can finally breathe a little bit easier," Mayor Brett Smiley told reporters.

There was no immediate indication of a motive in the twin shootings at two of the top universities in the United States.

"The groundwork that started in the city of Providence... led us to that connection," Perez said, without offering further details, with an upcoming press conference set in Boston. 

The shooting at Brown -- located in Providence, Rhode Island -- happened Saturday, when a man with a rifle burst into a campus building at the Ivy League college where students were taking exams. 

The man opened fire, killing two students and then fleeing.

The two students killed were Ella Cook, vice president of Brown's Republican Party association, and Mukhammad Aziz Umurzokov, originally from Uzbekistan, who had hoped to become a neurosurgeon.

One survivor was in critical but stable condition, five were in stable condition, and two had been discharged from hospital, Smiley said earlier in the day.

For days, investigators appeared to have little to go on, releasing images of a person of interest and an individual who was seen standing near that person in an effort to trace them.

Officials had given daily media updates at which they have voiced increasing frustration with the so far fruitless manhunt.

But then the case blew open. 

Authorities initially detained a man in connection with the shooting, but later released him.

The university has faced questions, including from President Donald Trump, about its security arrangements after it emerged that none of its 1,200 security cameras were linked to the police's surveillance system.

There have been more than 300 mass shootings in the United States so far this year, according to the Gun Violence Archive, which defines a mass shooting as four or more people shot. 

Attempts to restrict access to firearms still face political deadlock.