A dam collapsed in western Kenya early Monday, killing at least 40 people after a wall of water swept through houses and cut off a major road, police said.

The Old Kijabe Dam, located in the Mai Mahiu area of the Great Rift Valley region that is prone to flash floods, collapsed and water spilled downstream, carrying with it mud, rocks and uprooted trees, police official Stephen Kirui told The Associated Press.

Vehicles were entangled in the debris on one of Kenya’s busiest highways and paramedics treated the injured as waters submerged large areas.

Ongoing rains in Kenya have caused flooding that has already killed nearly 100 people and postponed the opening of schools. Heavy rains have been pounding the country since mid-March and the Meteorology Department has warned of more rainfall.

Kenya’s Interior Minister Kithure Kindiki ordered the inspection of all public and private dams and water reservoirs within 24 hours starting Monday afternoon to avert future incidents. The ministry said recommendations for evacuations and resettlement would be done after the inspection.

The Kenya National Highways Authority issued an alert warning motorists to brace for heavy traffic and debris that blocked the roads around Naivasha and Narok, west of the capital, Nairobi.