Militants attacked Pakistani Air Force Base Minhas in Kamra before dawn Thursday, triggering an intense gun battle with security forces, officials said.
Security forces were returning fire and special forces commandos were scrambled to respond to the attack at the base in Kamra, 60 kilometres (37 miles) northwest of Islamabad.
The security forces have cordoned off the area and started rescue operation.
Witnesses said they could hear gun and rocket fire coming from the facility, which contains a number of aircraft factories.
There was no immediate confirmation of the number of attackers or whether there were any casualties.
An emergency control room has been set up at the Air Force Headquarters to monitor the situation while Pakistan Army has been called in for help.
According to the sources, the terrorists entered base from Pind Suleman Makhan, a village adjoining the PAF facility, and launched attack at 2:30am