Pakistani authorities say hundreds of thousands of people are fleeing flash floods after having been warned to evacuate as the death toll from severe monsoon rains in Pakistan and neighboring India climbs to 457 people.

Ahmad Kamal, spokesman for the National Disaster Management Authority, says the Chenab River breached an embankment early Wednesday following a warning the day before.

The floods, which began in the Himalayan region between the two countries on Sept. 3, have flowed down to the plains, affecting more than 1.5 million people in Pakistan. The deluge is the worst since 2010, when some 1,700 people died in flooding in Pakistan.