Three people were killed and three others injured Friday in an explosion at a mine in the central Mexican municipality of Zacazonapan, authorities told Efe.

The blast occurred at a site where miners extract silver, gold, zinc and copper.

"Apparently they were conducting a detonation with explosives in the mine, a cave-in struck and there are people trapped," an emergency services official in Mexico state said.

He said injured miners were evacuated by helicopter to a hospital in Toluca, the state capital.

The mine is operated by Tizapa, a subsidiary of Peñoles.

The blast was caused "by human error," Mexico state Gov. Eruviel Avila said on Twitter, expressing regret over the loss of life.

The state Attorney General's Office will "carry out investigations in coordination with relevant federal authorities," the governor said.

Tizapa has yet to provide any information on the incident, though a company spokesman told Efe a statement would be forthcoming. EFE