At least four people were killed when militants attacked the airport in the northwestern city of Peshawar on Saturday and traded gunfire with soldiers, military and health officials said.
Pakistan's military rushed reinforcements to the scene of the attack, one of the most audacious raids by militants since an attack on an air base in August.
A health official said at least 26 people had been wounded, and that at least three of the dead were militants.
"An emergency has been declared in the hospital and all the surgeons have been called," said Umar Ayub, chief executive of the Khyber Teaching Hospital Peshawar. "All of them suffered bullet injuries and some of the injured are in critical condition."
Peshawar has witnessed many bomb attacks and shootings in recent years, but residents said it was the first time such a large attack had been staged on the airport.