"We never thought that it would be one of us. And it's so shocking, we can't accept it," said Ann Lau, a local resident who organized Monday night's candlelight vigil.

"When I heard about the news, I was honestly surprised at first because Monterey Park is a pretty safe and quiet neighborhood. And so for something like this to happen caught me off guard. But yeah, it's a devastating event. I came here because I want to support," added Chelsea Taruc, 24-year-old local resident.

Investigators collected 42 bullet casings from the scene of the shooting, one of California's bloodiest mass shootings, as they sought clues on Monday to what drove an elderly gunman to open fire and kill so many.

Authorities said he drove to another dance hall where a second, would-be attack was thwarted and later shot himself to death in his parked getaway vehicle as police closed in to make an arrest on Sunday, ending an intense manhunt some 12 hours after the rampage.

Ten people were killed and 10 others wounded when Tran opened fire at the Star Ballroom Dance Studio, a venue popular with older patrons of Asian descent, then drove off. One of the victims hospitalized in critical condition died of his wounds on Monday, Monterey Park Police Chief Scott Wiese told reporters.

All of the dead, six women and five men, were in their 50s, 60s and 70s, the coroner's office said.