Experts on Thursday continued burning off unexploded fireworks in an Ontario neighborhood rocked this week by explosions that left two people dead.
Controlled burns began Wednesday evening and the city of Ontario tweeted that they would continue until all hazardous materials are destroyed.
Another burn is scheduled for Friday morning, fire and police officials said during a Thursday evening news conference.
Additionally, three large fireworks deemed too dangerous to move will be burned in place Friday, Ontario Fire Chief Ray Gayk said.
Regional air quality officials advised that neighborhoods directly downwind might experience unhealthy air quality at times through Thursday.
The explosion of a large cache of fireworks Tuesday rained debris down over a wide area and dozens of residents were evacuated.
The FBI and a bomb squad are at the scene, where experts are sweeping and clearing an 80-house debris field to make sure it is safe. Building inspectors were also doing damage assessments in the neighborhood, officials said.
Many of the fireworks found at the scene were described as large, commercial-grade explosives that are not legal in California, but it is unclear how they ended up at the location.
Ontario Police Chief Mike Lorenz said local law enforcement is working with the FBI to try and trace where the fireworks came from and if any arrests are warranted. He indicated the investigation is still ongoing.
The two people who died in the blast were found in the backyard of the property and have not been formally identified.
However, two men associated with the property were reported missing and identified as 38-year-old Alex Paez and 20-year-old Cesar Paez. While Lorenz did not officially confirm them as the two people killed, a GoFundMe page created by a family member describes the pair as cousins who died in the massive blaze.
Several homes in the area remained evacuated Thursday morning.
A family whose dog hid after hearing the explosions Tuesday was not able to get their pet out when the home was evacuated.
They were reunited with Junior, a Chihuahua mix, on Thursday thanks to help from Ontario police officers.