PARIS (AP) — French prosecutors say they have opened a counterterrorism investigation into attempted murder after an attack at a high-security prison in northern France.

The Paris prosecutor's office can't confirm details of the Thursday afternoon attack at the Vendin le Vieil prison that French media say was launched by a knife-wielding inmate against several people.

French media say no one has been killed and no one is in a life-threatening condition.

The prosecutor's office said its investigation was launched by its anti-terrorism branch Thursday and centered on the attempted murder of civil servants.