A vast landfill site collapsed in Uganda’s capital city on Friday, killing at least 18 people, the Red Cross said. Eighteen was the latest number reported by the nonprofit on Sunday as searches drew on for people who still had not been accounted for, but Uganda Prime Minister Robinah Nabbanja said later that it had risen to 20. The death toll was expected to continue to climb.

Fourteen other people were injured when the Kiteezi landfill, which serves as a waste disposal site for much of Kampala, collapsed late Friday. At least two of the dead were children, Kampala Capital City Authority said in a statement.

No new survivors were rescued from the site on Sunday, the prime minister’s office said in a social media post. As of 6:30 p.m. in the local time zone, four people were missing, according to the office.

The collapse is believed to have been triggered by heavy rainfall. The precise details of what happened were unclear, but the city authority said there was a “structural failure in waste mass.”

Irene Nakasiita, a spokeswoman for the Uganda Red Cross, said the toll reached 18 after more bodies were retrieved from the scene Sunday.

“The assessment is not yet completed,” she said, adding that rainfall was slowing the efforts of rescue teams digging through heaps of trash.

The Kiteezi landfill is on a steep slope in an impoverished part of the city. Women and children who scavenge plastic waste for income frequently gather there, and some homes have been built close to the landfill.

Kampala authorities for years have considered closing the site and commissioning a larger area outside the city as a waste disposal site. It was not clear why the plan has failed to take off since 2016.

Ugandan President Yoweri Museveni ordered an investigation into the incident, asking in a series of posts on the social platform X why people were living in close proximity to an unstable heap of garbage.

“Who allowed people to live near such a potentially hazardous and dangerous heap?” Museveni said, adding that effluent from the site is hazardous enough that people should not be living there.