ONTARIO, Calif. (AP) — Authorities are destroying a massive cache of fireworks in a Southern California neighborhood rocked this week by explosions that left two people dead.

Tuesday’s blasts rained debris down over a wide area in the city of Ontario, about 35 miles (55 kilometers) east of Los Angeles, and dozens of residents were evacuated. Fireworks are illegal in Ontario, as in many California cities, and investigators are trying to figure out why the explosives were there.

Cousins Alex Paez, 38, and Cesar Paez, 20, were reported missing after the explosion. Their family says they are the two people who were killed, according to a GoFundMe page, although authorities have not yet officially confirmed the victims’ identities.

Officials on Thursday said experts have burned about 80 bins — each holding about 27 gallons (102.21 litres) — full of fireworks to safely destroy them. Regional air quality officials advised that neighborhoods directly downwind might experience unhealthy air quality at times.

Fire Chief Ray Gayk said he expects that another 80 bins will be burned Friday. The controlled burns began Wednesday evening, and the city of Ontario tweeted that they would continue until all hazardous materials are destroyed.

Authorities, including the FBI, are investigating where the huge stash of fireworks came from. Officials said the fireworks do not appear to be commercial-grade products, as they initially thought. Investigators are trying to track bar codes on the fireworks.

“We don’t understand why all of the fireworks were there,” Police Chief Mike Lorenz said.