Thirty-one people working in a massive underground tunnel in Los Angeles were rescued Wednesday night after a portion of the structure collapsed, officials said. Those rescued didn’t have any visible injuries,

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.

All 31 of the workers were safe after the collapse of an 18-foot in diameter tunnel that is part of a wastewater management project in the Wilmington section of the city, officials said.