At least five people have been killed and one wounded in a militant siege of Pakistan’s Karachi airport.

Doctor Seemi Jamali, who is head of the city’s main Jinnah Hospital, said early Monday morning five dead bodies had been brought in, and one injured person was also brought to the hospital.

She added that three were Airport Security Force (ASF) personnel and two were civilian employees of Pakistan International Airlines. The wounded was also an ASF official.

The attack, on Sunday night, has raised fears about the possibility of a prolonged siege similar to other brazen attacks on key installations in recent years.

Army spokesman Colonel Nayer said troops had been deployed from the Malir cantonment near their airport. “They have reached the scene,” he said.

A spokesman for Airport Security Force (ASF) said: “Four to five terrorists have managed to reach the runway, they are heavily armed with ammunition and grenades and ASF commandos have cordoned off the area along with police and rangers.

“A gun battle is continuing between terrorists and forces,” he added.

The spokesman said the gunmen had entered the airport by cutting through a barbed-wire fence at the airport’s old terminal which is no longer used for passengers but instead has offices, workshops and hangars.

“The old terminal is attached to the runways being used for the new airport’s flight operations,” he added.

Senior police official Rao Muhammad Anwar earlier placed the number of attackers at “four to six”, while a spokesman for the Civil Aviation Authority added all flights had been suspended.

Television footage showed plumes of smoke rising from the runway and fires where planes were parked. It had not been confirmed whether there were casualties on either side.

There has so far been no claim of responsibility for Sunday night’s incident but similar raids in the past have been claimed by Taliban militants who rose up against the Pakistani state in 2007 in an insurgency that has claimed thousands of lives.