MEXICO CITY (AP) — Rescuers said Wednesday that a collapse and landslide at a garbage dump north of Mexico City was so massive that it buried a crane and its operator.

The civil defense office in the Mexico City suburb of Naucalpan said the crane operator, and his crane, are still missing, after a hillside collapsed at the landfill Tuesday. Marines, police and rescue workers continued the search for the man on Wednesday.

It was not immediately clear what triggered the cave-in. The landfill was subsequently ordered closed by environmental authorities, apparently because it wasn't operating with proper safeguards.

Overfilled and overcapacity landfills have been a recurring problem in Mexico. They frequently accept more garbage than can be safely contained or covered with dirt, leaving noxious runoff leaching into local bodies of water.

Naucalpan has a particularly severe problem with the dumping of construction rubble, given the large number of apartment buildings being built in the suburbs.

The Naucalpan city government closed eight illegal dumps Tuesday, and said it had found 30 such illegal dumps since the beginning of 2022, and estimated there could be as many as 100.

It suggested the dumps may be run by criminals, noting “these spaces are guarded by armed men.”

Some landowners actually welcome the illegal dumping of rubble in gulches and gullies, to even out otherwise unbuildable land.