An Air France flight was forced to make an emergency landing on Friday after a passenger allegedly attacked an attendant and began pounding on the cockpit door.

According to Reuters.com , the Air France plane was en route from Paris, France, to New Delhi, India, when it was forced to divert to Sofia International Airport in Bulgaria due to a disruptive passenger.

The Indian man began acting strangely shortly after takeoff and was seen getting into verbal altercations with other travelers onboard. Eventually, the male passenger reportedly assaulted a flight attendant and then ran toward the cockpit, attacking the door with his hands.

“We are investigating both his actions and his motives,” National Investigation Agency official Ivailo Angelov told Reuters. “There is no reasonable explanation for his behavior.”

The pilot of the flight ordered an emergency landing in Bulgaria, where the plane was met by police and the disruptive passenger was removed. He was charged with endangering flight safety and could face up to 10 years in prison if convicted.

Once the situation was handled, the Air France plane departed from the Bulgarian airport and continued its flight to New Delhi.

Attacks on flight attendants have become too common, as a disruptive passenger on a Delta Air Lines flight was fined $27,500 by the Federal Aviation Administration (FAA) for striking a crew member in the face last year.