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.

An investigation is underway to determine what led to a tunnel, under construction for the Los Angeles County Sanitation Districts, to partially collapse in Wilmington on Wednesday night, July 9 — prompting the rescue of 31 employees and a halt to work for an undetermined amount of time.

After an 18-foot-diameter tunnel collapsed at a work site in Wilmington, 31 people were extricated unhurt. No one was missing.