A Florida State University graduate opened fire at the crowded library of the university, wounding three people on Thursday, CNN reported.

The gunman was shot dead by police. One of the wounded, a student, was in critical condition. The other two of the wounded are a student and an employee.

The motives for the attack were unknown. The shooting has raised concerns about safety at US schools and will add fuel to long-running debate about gun control in the country.

Police identified the gunman as Myron May and said he was in a state of crisis, fearing that government agencies were targeting him.