Guatemala City authorities say that 24 people are listed as missing two days after a massive slope of trash collapsed, killing at least four people.

Hundreds of rescuers are still picking through the garbage dump looking for survivors or bodies.

The city spokesman said Friday the problem is that many people work informally as garbage pickers at the dump, and only some were officially registered as present when the collapse occurred on Wednesday.

City spokesman Carlos Sandoval said that ‘of the missing people, seven are registered’ as garbage pickers, who poke through trash looking for recyclable materials to sell.

The others are believed to be people who were working without permission at the dump.

About 1,200 registered garbage pickers work at the massive dump.