Landslides have left at least 36 people dead in Uganda with rescue workers warning the death toll will rise.

Hundreds have lost homes and livestock after torrential rains caused the River Suume to burst its banks, triggering landslides that devastated two villages in the mountainous eastern district of Bududa on Thursday afternoon.

Sowed Mansur, the regional police spokesperson, said 36 bodies had been retrieved by Friday morning. In Maludu, part of a primary school has disappeared under the mud, leaving more than 200 pupils missing.

The local media put the death toll at 40, with an estimated 400 people still missing, and dozens of injured survivors have been hospitalised. Search and rescue efforts continue.

“The heavy downpour and muddy ground is making our rescue efforts for the missing people and recoveries of bodies difficult. The teams carrying relief and necessary assistance can’t access the scene, since a connecting bridge was washed away,” said Mansur.

“Both animals and people were swept away in this disaster,” said Uganda Red Cross Society in a statement. “Our community volunteers did their best to rescue some people from the debris.”

President Yoweri Museveni wrote in a tweet: “I have received the sad news of landslides wreaking havoc in Bududa district, killing a yet to be specified number of residents. The government has dispatched rescue teams to the affected areas.”

“The government will look at the other options available to stop further occurrences of these disasters,” he added.

A government minister claimed people had been advised to leave the area.

“We had earlier predicted about a problem [landslides] in Bududa. We warned and advised those living in endangered areas to leave. But they ignored, resisted and insisted to stay. Now this tragedy has struck with devastating effects,” said Hillary Onek, minister for disasters preparedness and relief.

“Some of them were shifted from there but went back. We are going to see how to safeguard the people at risk of the rains and landslides.”

Residents bear bodies away from the scene of a landslide in Bududa, Uganda. Photograph: Reuters TV/Reuters

In 2010, the government resettled hundreds of people who survived landslides in Bududa to the mid-western district of Kiryandongo, but many returned. At least 300 people were killed and thousands were forced to flee after a landslide buried three villages in March 2010.

The prime minister, Ruhakana Rugunda, said the government was helping more than 500 people affected by the disaster.

“Government has dispatched relief supplies including food, blankets, tents, tarpaulins, jerrycans and saucepans,” said Rugunda.

More than 100,000 people remain at a risk of landslides in the mountainous Elgon and Rwenzori sub-regions, with up to 20,000 of them likely to be displaced in the next four months, according to the Office of the Prime Minister.