Flash floods triggered by torrential rains Sunday killed at least 45 people in northwest Pakistan, officials said.

Rains started overnight Saturday and caused flash flooding in several districts of Khyber Pakhtunkhwa province, said a Pakistani national disaster management official, Latif ur Rehman.

Another 34 people were admitted to hospitals with injuries, he said.

Flash floods are commonly triggered during South Asia's summer monsoon season.  Pre-monsoon rains like the current downpour frequently cause damage in Pakistan -- particularly in rural villages with minimal infrastructure.

Residents of scores of villages close to rivers were given warnings to vacate and leave for safer places, Rehman said.

"We're left on our own. Nobody from the government is coming to help us," said Habib Khan, a resident of the northern Swat valley, talking to a local TV news channel.

The channel showed damaged houses and submerged streets in the valley and other parts of the northwestern province.