NITEROI, Brazil — As many as 200 people were buried under tons of mud and feared dead on Thursday after a slum built atop a former landfill gave way in the latest deadly landslide to hit metro Rio de Janeiro.

If confirmed, the deaths would raise the toll sharply from the 153 people already known to have died this week in slides triggered by record rains.

“We know that about 60 houses were buried,” Rio state health secretary Sergio Cortes told The Associated Press. “It is hard to say exactly how many people were buried under the mud as well, but a worst-case scenario is 200.”

The slide that hit late Wednesday was a wall of black earth and garbage about 40 feet high that plowed through the Morro Bumba shantytown before coming to a halt along the edge of road in Niteroi, a city of about 500,000 across the bay from Rio.

On Thursday, crews with heavy machinery dug through the debris and about a dozen trucks lined up to haul it off. News broadcasts showed one house on top of the hill with only two walls standing, and a bed, a night stand and a television inside. Everything else went down with the slide.

Residents told local media that a small church, a day care center and several business were in the area and likely buried.

“In our experience, it’s an instant death” for anyone caught in such a slide, said Pedro Machado of Rio state’s Civil Defense department.

The ground underneath the shantytown — decades of accumulated trash — was especially unstable and vulnerable to the heavy rains, said Agostinho Guerreiro, president of Rio’s main association of engineers and architects.

“It is very fragile soil. It couldn’t hold (the rain). The houses came down, destroying the ones below them,” Guerreiro told Globo TV. “It was a tragedy foretold.”

The federal government announced an emergency fund of 200 million reals ($114 million) to help the state deal with the mudslides and flooding.

The fire department spokesman said six bodies had been found so far in Morro Bumba and 28 people were rescued after the mudslide hit late Wednesday.

Alves Souza, commander of the firefighters in the Niteroi rescue operations, said the wet, steep terrain posed a continued threat to anyone trapped in the wreckage and emergency crews as well.

“The work is very intense, given the fact that the volume of material we have here is very large,” Souza said.