Flooding has ravaged hundreds of villages in Pakistan's main province of Punjab, destroying homes, soaking crops and threatening more lives.
Aid workers warned that bloated rivers would surge south soon, flooding more areas.
This year's monsoon season has caused the worst flooding in Pakistan in living memory and already killed more than 1,500 people.
The UN scrambled to provide food and other assistance to some 3.2 million affected people in a nation already struggling with an Islamist militancy and a poor economy.
After causing huge destruction in Pakistan's volatile north-west region, floodwaters deluged villages and some urban centres in Punjab, the richest and most populous province.
The army used boats and helicopters to move stranded villagers to higher ground.
Water was so high, only treetops and uppermost floors of some buildings were visible in large tracts of Kot Addu and the nearby area of Layyah in the south of the province.
Military spokesman Major General Nadir Zeb told reporters at least 30,000 people have been rescued from flood-hit zones in Kot Addu and areas over the previous 72 hours. He warned of more flooding as more rains were forecast in the next few days.
"People must cooperate with us, and they must leave those areas where floods are going to hit," he said.
Monsoon season in Pakistan usually lasts about three months, through mid-September. In a typical year, the country gets an average 5.4ins of rainfall during the monsoon season. This year, it already has received 6.3ins, said Muhammad Hanif, head of the National Weather Forecasting Centre in Islamabad.