The governor of California has declared a state of emergency because of an overheated chemical tank

California’s governor declared a state of emergency in Orange County on Saturday as emergency workers continued efforts to cool an overheated chemical storage tank and prevent it from exploding.

No injuries were reported after a pressurized tank overheated Thursday and began spewing steam in Garden Grove, according to the Orange County Fire Authority. Evacuation orders were issued for 40,000 people, and several shelters were opened Friday night, including three high schools.

California Gov. Gavin Newsom said in his emergency declaration that shelters are being opened.

“State agencies are supporting affected communities to protect public safety, and assisting local officials as response efforts continue,” Newsom said on social media.

The announcement comes shortly after officials scaled back on earlier optimistic temperature readings.

Orange County Fire Authority Chief Craig Covey said Friday afternoon, after hours of emergency crews spraying water to cool it, the tank and its temperature appeared to be stable. However, he announced on Saturday that this is no longer the case.

“Those temperatures we were doing with the drone, we read on the internet [exterior] … not covering the internal temperatures,” Covey said in a video caption posted on social media.

To get the actual indoor temperature, Covey said, officials called late Friday “to go back and get upset.”

He said workers initially responded defensively as a precautionary measure, but now responders are participating in more dangerous activities.

“We put people in danger last night,” Covey said. Crews went to the tank and found the temperature readings had risen to 90 F (32 C) Friday night, from 77 F (25) that morning.

Covey previously said the main concern is that the tank could fail and crack, releasing the chemical to the ground, or it could explode.

The tank is owned by GKN Aerospace, which makes parts for commercial and military aircraft.

The tank holds between 6,000 and 7,000 liters (22,700 and 26,500 liters) of methyl methacrylate, which is used to make plastic parts.

If the chemical is heated, it can release vapors that are harmful to human health. It can cause breathing problems, itching and burning of the eyes, nausea and headache, said Dr. Regina Chinsio-Kwong, Orange County health officer.

“Letting this thing fail and blow up is not acceptable to us,” Covey said Saturday, adding that officials are making contingency plans for the worst-case scenario, such as building dikes and creating sandbag barriers.

“Our goal is … not to let that happen, not to let it ruin our community, not to let it ruin our neighborhood.”