A smoke alarm on board an IndiGo flight forced the plane to make an emergency landing at Kolkata airport and passengers to be evacuated.

A passenger on the 6E-237 from Jaipur to Kolkata made a video that showed smoke inside the cabin as it neared its destination. A second video showed a few passengers evacuating the aircraft using an emergency slide after it landed at the airport.

According to reports, the pilot issued a “May Day” call, meant be used to seek help in times of distress. After landing, the airport was taken to an isolation bay where aft or emergency passenger chutes were deployed so that passengers could exit. However, most of them exited using the front ladder.

The airline said all the passengers and crew were safe and there were no earlier reports of malfunction of the aircraft. The Aircraft Accident Investigation Board launched a probe into the incident and asked the airline to submit a report after a detailed inspection.