Thirty-one men working in a massive underground tunnel in Los Angeles were rescued Wednesday night after a portion of the structure collapsed, officials said.

An industrial tunnel in Los Angeles collapsed partially. None of those rescued had major injuries, authorities said.

Workers were 400 feet (121 meters) underground and as much as 6 miles (9.6 kilometers) inside from the only entrance when the cave-in Wednesday evening threatened to trap them on the far side of the tunnel’s boring machine,