LOS ANGELES: Thirty-one workers have been safely removed from an industrial tunnel under construction in Los Angeles after part of it collapsed on Wednesday, the Los Angeles Fire Department said.

The collapse occurred 8 to 9.7 kilometres from the tunnel's sole entrance in an industrial section of the city. Aerial footage from local television showed workers being lifted up through the tunnel's entrance.

Some workers on the other side of the collapsed portion of the tunnel scrambled over a 12 to 15-foot-tall mound of loose soil and reached several coworkers on the other side. The workers were then shuttled several at a time by tunnel vehicle to the opening.

Paramedics were evaluating 27 of the workers removed from the tunnel.

The tunnel is under construction to eventually carry wastewater. It's 18 feet wide, LAFD said.

More than 100 LAFD workers were assigned to the scene, including those who specialise in rescues from confined spaces.