Islamabad, Pakistan ? President Gen. Pervez Musharraf survived an apparent assassination attempt Friday when shots were fired at his aircraft as it took off from a military base, authorities and witnesses said.

It was not immediately clear whether there was any connection between the shooting incident and the ongoing siege by Pakistani troops of a radical mosque in the capital. At least 19 people are reported to have died in the mosque confrontation, which began Tuesday.

Pakistan has been gripped by a sense of crisis over the past four months as a pro-democracy movement has challenged Musharraf’s attempts to sideline the chief justice of the Supreme Court, who might have posed an obstacle to the president’s efforts to secure another term of leadership virtually unchallenged.

Despite the turmoil, the Bush administration has stood by Musharraf, who is considered a key ally in the fight against the Taliban and other Islamic insurgents in Pakistan and Afghanistan. Among American policymakers, it is widely believed that the toppling of the general, who seized power in a bloodless coup eight years ago, could create a dangerous power vacuum in nuclear-armed Pakistan, which is home to many militant groups.

Musharraf’s aircraft came under fire as it took off from the Chakala air base in Rawalpindi, a garrison city adjoining the capital. Police said two anti-aircraft guns and a light machine gun were seized from a house that lay directly beneath the flight path of the base and also below the path of planes arriving and departing from Islamabad’s international airport.

The president’s plane landed without incident in Turbat, in Pakistan’s south, which was hit hard by flooding in June.

Security officials in Rawalpindi said 25 light machine-gun rounds apparently were fired toward the aircraft.

Musharraf has been the target of at least three previous assassination bids, all of which were believed to have been masterminded by Islamic militants.