SANTA PAULA, Calif. (KABC) -- Ventura County fire officials remained on the scene Wednesday to watch for flare-ups at a Santa Paula waste facility following a fiery explosion the day before.
Authorities said the danger is easing up, but they're watching over a handful of smoldering hot spots at the site in an agricultural area in the 800 block of Mission Rock Road, where a vacuum truck exploded Tuesday morning.
The explosion at Santa Clara Waste Water Co. spread approximately 1,200 gallons of a chemical mixture that contained sulfuric acid and an organic peroxide, officials said.
PHOTOS: Flames, smoke after Santa Paula vacuum truck explosion
The combination of these substances results in a highly toxic and combustible material, according to Ventura County fire Capt. Mike Lindbery. He said the substance spontaneously ignited under fire engine tires and firefighters' boots.
"We need to determine exactly what this material is," he said. "How do we neutralize it, and how do we clean it up?"
A private contractor will be in charge of the cleanup, under the supervision of county health officials and the federal Environmental Protection Agency.
Two drivers on the vacuum truck, three firefighters, hospital medical staff and a few residents required decontamination treatment for breathing problems, red eyes and skin rashes, said a spokeswoman for the Ventura County Fire Department.
Authorities said 37 people were treated at area hospitals. All were expected to be released, except the driver of the truck that exploded, who suffered traumatic injuries.
Seventy-one dogs trapped inside the Canine Adoption and Rescue League near to the spill were also evacuated Wednesday.
"Everything looks to be pretty good. There's no bad respiratory distress, there's a little eye irritation, so we're very happy about that," said Mary Saputo with the Canine Adoption and Rescue League.
The dogs were being evaluated and decontaminated.
VIDEO: AIR7 HD over Santa Paula hazmat fire
After the initial explosions, firefighters backed off and let the blaze burn itself out. They were concerned that putting water on the chemical would potentially flush it into the nearby Santa Clara River.
Due to heavy smoke drifting from the scene, authorities ordered the evacuation of the area within a mile of the plant. This was later reduced to half a mile.
The cause of the initial explosion has not been determined.
Residents with questions can call a public information hotline at (805) 465-6650.
The Associated Press contributed to this report.