Irvine Police Department officers responded at about midnight to a report of hazardous conditions at a residence in the 40 block of Gardenpath in Turtle Ridge, according to the Orange County Fire Authority.
Police found what was initially described as a clandestine narcotics lab but was later said to be simply a hazardous materials investigation.
A pair of officers reported feeling ill after entering the home, and were transported to a hospital as a precaution, OCFA Capt. Larry Kurtz said. They were subsequently released and were both "absolutely fine," Kurtz said.
After powder and canisters were found inside the home, according to police, a county hazmat team was summoned, along with SWAT officers wearing oxygen tanks and armed with semiautomatic weapons.
The residence was inspected after a warrant was obtained, police said.
Several neighbors were evacuated from their homes as the search was conducted. Among them was Gordon Yang, who heard a knock at his door.
"The knock became very persistent, and then so I went down to check what happened," he said. "It's the police, and the police said, 'You need to evacuate as soon as possible.'"
Fire officials said materials were identified as calcium sulfate and calcium carbonate, but no dangerous substances were located.
The resident of the searched home, whose 911 call had prompted the initial police response, was detained and remained in custody Tuesday afternoon, authorities said.