Thirteen people were killed and six others injured late Friday when a fire broke out at a bar in the northern French city of Rouen.

An accidental explosion in Cuba Libre's basement is believed to be the cause of the fire, according to Paris Normandie.

Most of the victims were between the ages of 18 to 25 and had been celebrating a birthday at the bar just as the Olympics opening ceremony commenced.

The identities of those killed have not been shared with the public. Authorities said early Saturday they will continue to investigate the explosion and speak with witnesses.