At least two people were killed and several others injured Thursday when a small plane crashed into a factory in California, in the western US, police said.

The crash happened in the early afternoon at the municipal airport of Fullerton, a small city about 40 kilometers southeast of Los Angeles. The cause of the accident is not yet known.

“We have two confirmed deaths,” Fullerton police said via X.

Another 18 people were injured, of which “ten were transported to area hospitals for treatment” and “eight were treated at the scene” and allowed to leave, according to the same source.

It is not yet clear whether the dead were aboard the small tourist plane or worked at the unit where it went down, a Fullerton police officer told local television station KTLA.

In visual material broadcast by local media, a huge hole can be seen in the roof of a factory, from where smoke is coming out.

“All we heard was a loud bang, ‘boom’, that was it. Then we started running” toward the exit of the plant, Jerome Cruz, who works at the plant, told CBS News.

The plane that crashed was a small four-seater Van’s Aircraft RV-10, according to the US Civil Aviation Administration (FAA), which has begun an investigation.

In November, another plane crashed near the Fullerton airport, injuring two people.