Heavily armed gunmen have attacked Karachi’s international airport, killing at least five people and hurling grenades.
Pakistani media reported between four and 10 gunmen had attacked Jinnah International Airport’s old terminal.
Security personnel have sealed off the airport and army commandos have been called in, with gunfire continuing.
All operations at the terminal have been suspended and all flights to the airport are being diverted.
Staff are being evacuated.
The dead were said to be security guards from the Airport Security Force (ASF) and airline workers.
A doctor at Jinnah Hospital told Associated Press five bodies had been brought there, as well as one wounded person.
Dawn News said the gunmen had infiltrated from the Fokker Gate area. Some reports said they had cut through a barbed wire fence.
There is no indication yet who is carrying out the attack.
Geo News said two attackers were also reported dead and that smoke was billowing from the terminal.
An ASF spokesman told Agence France-Presse that the gunmen had reached the runway and that a “gun battle is continuing between terrorists and [armed] forces”.
An AFP reporter saw used gun magazines littering the engineering section where the first exchange took place and said that the previously heavy gunfire was now more sporadic.
Dawn reported that some attackers had managed to get inside a plane and that three aircraft had been damaged.
Sarmad Hussain, an official with Pakistan International Airlines, told AP: “I was working at my office when I heard big blasts – several blasts – and then there were heavy gunshots.”
He said he and a colleague escaped by jumping from a window. His colleague broke a leg.
The terminal is not normally used for commercial flights but for cargo and special VIP operations.
Sindh’s Chief Minister Qaim Ali Shah is said to have arrived at the scene.
Pakistan has been fighting an Islamist insurgency for more than a decade, with the Pakistani Taliban the main militant group.
Pakistan’s Prime Minister Nawaz Sharif recently told the BBC he was still hopeful his peace initiative with the Taliban could succeed.
But little headway has been made since February and there have been frequent violent clashes.
Karachi has been a target for many insurgent attacks.
Gunmen attacked the Mehran naval base there in 2011, killing 10 personnel and destroying two aircraft in a 17-hour siege.