Twenty-three workers at a hydroelectric power plant in Uttarakhand state died after water gushed into the facility on Saturday, state disaster management minister Yashpal Arya said.

Arya said three fire department personnel died in a riverside village in the state, which is in the Himalayan foothills.

"They were washed way from their fire station," Arya said, adding there had been seven other deaths in the region since the floods began early Saturday after heavy rains.

The state's Uttarkashi district is a popular Hindu pilgrimage site and some 700 pilgrims who were visiting shrines in the area had been stranded by the floods, Arya said.

The pilgrims became trapped after the floods wiped out roads, cutting off 80 Uttarkashi villages from the rest of Uttarakhand, he said.

"Rescue teams have been sent" to help those affected, Arya said, adding the floods destroyed 90 homes and 50 guest houses, with scores more threatened.

Torrential rains on Friday night also hit the nearby state of Himachal Pradesh, drowning a man in his vehicle, washing away several bridges and partly destroying a key highway.

While monsoon rains have failed to appear in many regions this year, other places have been inundated. Rains in the northeast last month killed more than 120 people and forced another six million to flee their homes.