Some 200 workers at the Hanford Nuclear Site in Washington state were ordered to "take cover" Tuesday after a 20-foot section of tunnel containing "contaminated materials" collapsed, the U.S. Department of Energy reported.
The alert was declared at 8:26 a.m. local time after the cave-in covered "railroad tunnels near a former chemical processing plant," the feds said.
All workers at the plant, which sits along the Columbia River, were ordered inside and access to the affected area is now "restricted to protect employees."
"There are no reports of injuries, no reports of radiological release," said Destry Henderson, deputy news manager for the Hanford Joint Information Center. "I would underscore this is confined to a small area of the Hanford site."