Islamabad, Pakistan (CNN) -- Flooding caused by monsoon rain has killed more than 400 people across Pakistan, a provincial government official said Friday.

Mian Iftikhar Hussain, the Khyber Pakhtunkhwa province information minister, said the death toll is now 408 people in that province and 25 in Pakistani-controlled Kashmir.

Qamar-uz-Zaman Chaudhry, the head of the Pakistan meteorological department, told CNN the 300 mm, or 11.8 inches, of rain recorded in Khyber Pakhtunkhwa is the most ever in Pakistan.

Many of the victims died when floodwaters swept away hundreds of mud houses in parts of Swat Valley and the districts of Shangla and Tank, according to Bashir Ahmed Bilour, a provincial minister in Khyber Pakhtunkhwa.

Rushing water also has washed away thousands of acres of crops and dozens of government buildings, local businesses and schools, Bilour said.

Hussain said floodwater has cut off the Swat Valley and the districts of Shangla and Peshawar. There is no way to get to these areas by road, he said.

Earlier Friday the head of Pakistan's National Disaster Management Authority said flooding had killed at least 150 people and injured 90 since Wednesday. Retired Lt. Gen. Nadeem Ahmed said 90 people were still missing.

The Pakistani Air Force is helping with rescue efforts, spokesman Tariq Yazdanie said in an interview on Pakistani TV.

The recent torrential rains have broken all previous records of rainfall in the country, he said.

The U.N. refugee agency dispatched the first shipment of aid for flood victims in the region Thursday, the state-run Associated Press of Pakistan reported.

APP said the supplies include 585 tents, 2,700 plastic sheets, 1,760 kitchen sets and 4,000 plastic mats.

At the same time, a top official in Khyber Pakhtunkhwa province pressed Pakistan's president for help, according to APP.

The news agency said Assembly Speaker Karamatullah Khan told legislators he had asked President Asif Ali Zardari for a supply of emergency boats.

Photographs from Getty Images showed flood victims struggling to cross a swollen river in the town of Nowshera. The pictures showed children being ferried across the water in overcrowded boats, and more able-bodied people helping the elderly to higher ground.

Supplies from the U.N. agency will go first to the two hard-hit villages of Talli and Sultan Kot in Sibi district, APP said.

The U.S.-based group Save the Children said it will distribute plastic sheeting for shelters, household supplies and hygiene kits to about 1,000 families over the next two days.

Journalist Nasir Habib contributed to this report.