Pakistani children play in a refugee camp Sunday in Swabi, in northwest Pakistan. Tens of thousands have fled fighting between the military and the Taliban in Swat Valley, adding a humanitarian crisis to the nuclear-armed nation’s economic, political and other woes.

Mingora, Pakistan ? Tens of thousands of civilians, many on foot or donkey-led carts, took advantage of a lifted curfew to flee Pakistan’s embattled Swat Valley on Sunday, while the army said it had killed 400 to 500 militants in its battle against the Taliban.

The hemorrhaging of residents from a scenic valley that once attracted hordes of tourists threatened to greatly exacerbate an existing internal refugee crisis for a nuclear-armed nation already facing economic, political and other woes.

The army offensive has garnered praise from the U.S., which wants Pakistan to root out havens on its soil where Taliban militants can plan attacks on American and NATO forces across the border in Afghanistan. In an interview aired Sunday, Pakistan’s president urged international support for the fight and insisted the army had enough troops in the northwest to handle the threat.

As they left Swat’s main town of Mingora, some residents cursed the situation and condemned the Taliban, while others blamed Pakistani leaders for bowing to the West. “Show our picture to your master America and get money from him,” some taunted.

The desperate Swat residents were trying to leave any way they could — on motorbikes, animal-pulled carts, rickshaws or foot. A ban on civilian vehicles entering the valley complicated the exodus for those without cars. Some chided an Associated Press reporter for slowing them down by asking questions.

“We are going out only with our clothes and a few things to eat on the long journey,” said Rehmat Alam, a 40-year-old medical technician walking out of Mingora with 18 other relatives. “We just got out relying on God because there is no one else to help us.”

Fighter jets and helicopter gunships have pounded Swat and surrounding districts over the past few days after Taliban fighters in the valley moved out and tried to impose their reign in other areas, including a stretch just 60 miles from the capital, Islamabad.

The army’s nine-hour suspension of the curfew Sunday could signal a more intense operation now that more civilians have left. Army spokesman Maj. Gen. Athar Abbas said 400 to 500 militants had been killed since the operation’s launch last week.