Thousands of people are fleeing Pakistan's violence-hit Swat district after the army temporarily lifted a curfew.
Local residents trapped by fighting between troops and Taleban militants were given seven hours to leave.
The army is trying to reverse militant advances in the area, in what the prime minister has called a "fight for the survival of the country".
Analysts say the lifting of the curfew is a sign that the army offensive is likely to intensify in the coming days.
The curfew was lifted at 0600 local time to allow residents to leave Swat's main town of Mingora and the nearby towns of Kambar and Raheemabad.
As dawn broke in Mingora, thousands of civilians began to leave.
Men, women, children and the elderly were seen moving along the road that leads out of the region.
The lucky ones were able to get some sort of transport, ranging from a local bus to a donkey cart.
Due to the intensity of the fighting and the cutting of phone networks, it is difficult to get independent information on the fighting or verify the army's claim that it has killed nearly 200 militants in the past two days alone.
Pakistan's government signed a peace agreement with the Swat Taleban in February, allowing Sharia law there, a move sharply criticised by Washington.
The militants then moved towards the capital, Islamabad, causing further alarm.
Up to 15,000 troops have now been deployed in the Swat valley and neighbouring areas to take on up to 5,000 militants. The military has said it intends to "eliminate" the Taleban fighters.
The fighting has already displaced some 200,000 people, while a further 300,000 are estimated to be on the move or poised to flee, the UN says.
On Saturday the government said that refugee camps would be set up in Peshawar, the capital of North West Frontier Province, and to the north-east in Naushara.