Mumbai: After the pilot notices a smoke alarm from the cargo hold, a Mumbai-Hyderabad SpiceJet flight with 140 passengers on board on Friday landed under emergency conditions at the city airport.

The aircraft, SG-401, which took off from Mumbai airport at around 5.30 am returned and landed safely at 6.05 am here.

"The pilot on board SG-401 observed the smoke alarm in the cargo hold. Following the standard safety procedures and checklists, the captain activated the fire extinguisher in the cargo hold and requested for priority landing," SpiceJet said in a release issued here.

The plane was taken to an isolation area and investigating agencies like the Air Safety wing of the DGCA, the bomb detection and disposal squad, the Bureau of Civil Aviation Safety and airport fire agencies are inspecting the aircraft, it said.

The private airline said that all passengers were deplaned safely and arrangements were made to send the passengers to their destination with least delay.

Earlier, a Mumbai International Airport Limited (MIAL) official said all passengers were disembarked by 6.30 am.