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,

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.

None of the 31 construction workers rescued in the tunnel sustained visible injuries, according to LAFD. Firefighters said construction workers climbed over a roughly 12 to 15-foot pile of dirt to escape.