Air France says one of its jets had what investigators call a “serious incident” by flying too close to a volcano while maneuvering around a storm on a flight into Cameroon.

Flight 953 took off from Malabo in Equatorial Guinea on May 2 and was cruising toward Douala, Cameroon’s largest city, when the pilot rerouted the Boeing 777 to avoid a storm.

A ground-proximity alarm in the cockpit sounded when the jet, with 37 people aboard, flew too near Mount Cameroon, a 4,095-meter (13,435 feet) active volcano whose last eruption was reported in 2012.

In a statement Wednesday, Air France said pilots “responded immediately by applying the appropriate procedure.” The flight landed in Douala without further incident.

France’s air safety authorities have opened an investigation.

(AP)