40,000 people under evacuation orders after chemical tank leak in Southern California

Jeff Gritchen/The Orange County Register/AP

"This is not precautionary. … This thing is going to fail, and we don't know when," said Garden Grove Fire Chief Craig Covey during a Friday afternoon press conference. "We're doing our best to figure out when or how we can prevent it."

Covey said the tank could fail and crack, releasing the chemical onto the ground, or it could explode.

"We understand that this is frightening," Garden Grove Mayor Stephanie Klopfenstein said at the news conference. "But the evacuation orders are in place for your safety."

Garden Grove is about 38 miles (61 kilometers) south of downtown Los Angeles and less than a mile from Disneyland's two theme parks, which were not under evacuation orders Friday. The inland Southern California city is known for its vibrant Vietnamese community, one of the largest of any U.S. city.

Covey said crews have created containment barriers with sandbags in case there is a chemical spill from the tank to prevent the chemical from getting into storm drains or reaching creeks or the nearby ocean.

He said the chemical is highly volatile, toxic and flammable.

"We are setting up these evacuations in preparation for these two options: it fails, or it blows up," Covey said earlier in a video update posted on social media. "Please follow our requests and orders for evacuations."

Crews were initially successful and were able neutralize one of two damaged tanks but Covey said they determined Friday morning that the remaining tank was "in the biggest crisis."

GKN Aerospace said specialized hazardous material teams are assessing the situation.

"There are no reports of injuries at this time and our priority remains the safety of our employees, responders, and the surrounding community," a spokesperson said in an emailed statement. "We will provide verified updates as soon as more information becomes available."