Three policemen have been killed in a shootout at Mexico City’s main airport, officials say.

The security ministry said the federal officers had been sent to detain suspects in a drug trafficking case.

Passengers dived for cover when the suspects opened fire, killing two officers immediately and injuring a third who later died in hospital.

The area was sealed off but flights were reported to be operating normally in and out of the airport.

Witnesses said the shooting happened in the food hall of Terminal 2.