Hazardous waste workers inside a sealed enclosure at Los Alamos National Laboratory drilled into an old container releasing an unknown gas that flashed on contact with the air, according to Kevin Roark a laboratory spokesperson, who had just returned from the site. He said the containers under investigation at the time looked like “old fire extinguishers.”

A hazardous materials team was dispatched to Material Disposal Area B, LANL’s oldest hazardous waste area on the east edge of the town site. A Los Alamos County emergency official sent out a reverse-911 telephone call warning residents. DP Road across from the dump was closed, and occupants of businesses along the road were asked to stay inside. No injuries were reported and an all-clear was sounded about two hours later.

The unknown contents will be identified by lab chemists as part of a routine process for remediating the containers.