An emergency has been declared following a tunnel collapse at a US nuclear site.
Hundreds of workers at the Hanford Plutonium Plant in Washington state have been forced to "take cover" following the cave-in.
No workers were inside the tunnel when it collapsed but nearby crews were evacuated as a precaution.
A management message to workers said to "secure ventilation in your building" and to "refrain from eating or drinking," the Independent reports.
Reports indicate that road work nearby may have triggered the collapse.
"There are concerns about subsidence in the soil covering railroad tunnels near a former chemical processing facility," the Department of Energy said in a statement.
"The tunnels contain contaminated materials."
Tanks at the site had previously been leaking toxic vapours and chemicals that are linked to cancer, brain damage and lung damage, the Independent says.
The location has been called "the most toxic place in America" and "an underground Chernobyl waiting to happen" by experts.