ALGIERS — Unknown attackers fired rockets on Friday at a gas facility in the Sahara in Algeria, the energy companies Statoil and BP said. There were no immediate reports of injuries.

The gas facility, Krechba, which is jointly operated by Statoil of Norway and BP of Britain, is overseen by the Algerian state-run gas company Sonatrach.

Statoil said the Krechba facility had been “hit by explosive munitions fired from a distance.” The company said it had been in touch with its three employees there, who were safe and had not been hurt.

BP said in a statement that there had been no reports of injuries to its employees and that the facility had been shut down as a safety precaution. It did not say how many people worked there.