Bangkok, Thailand ? Flash floods triggered by days of heavy rain killed at least 50 people in mountainous northern Thailand and left thousands trapped on rooftops and in trees, officials said Tuesday.

Other victims were believed trapped under tons of mud from a landslide that engulfed dozens of houses in the Lablae district of Uttaradit province.

Tens of thousands of households had no power.

“The situation is still confused because in several areas the rescue teams have not yet arrived and electricity is cut off in the entire Lablae district,” said Saman Pangwatcharakorn, chief of the province’s disaster prevention and rescue center.

By Tuesday evening, some 40 bodies had been recovered in Uttaradit and another 40 people were listed as missing, Saman said.

“We believe that the death toll will rise because rescue teams are still unable to get into villages where the landslide hit the houses of villagers,” said Nitipat Pimpiriyakul, chief of the province’s disaster center.