Security forces at Pakistan's busiest airport in the city of Karachi have come under attack, a day after militants stormed one of its terminals.
Officials say gunmen on motorbikes shot at a security training camp just outside the airport and fled.
Subsequent firing which lasted for up to an hour was shots fired by the army and police at the scene, officials say.
Flights at the airport are resuming. The Pakistani Taliban say they carried out both attacks.
The gun and bomb attack on the airport's cargo terminal on Sunday left at least 38 dead, including the attackers.
Reports say the attack began after militants pulled up a vehicle and began firing. Officials said the gunfire was directed towards their camp, but no gunmen penetrated the airport security perimeter.
The heavy weapons and sustained gunfire seems to have been the concerted army response so close to the scene of the airport attack.
Pakistan's Prime Minister Nawaz Sharif has said the attackers should be "pursued and eliminated".
The military has sealed off the area and are conducting intensive search operations in the area.
Several flights were turned back - one shortly before it was due to land - as they were en route to Karachi, local media reports say.
The death toll from Sunday night's airport raid rose sharply overnight after nine more bodies were discovered, seven of them in a cold storage facility.
This latest violence comes against the backdrop of a major split in the Pakistani Taliban, and threats of retaliation following military operations against Pakistan's tribal north-west.
It has brought the government of Sharif under renewed pressure to order tough action against the Taliban, correspondents say.
Early on Tuesday the Pakistani military carried out air strikes in tribal areas in the north-west Khyber region, killing at least 15 militants, officials say.