A 72-year-old gunman opened fire in a California dance hall on Saturday night, killing 10 people and injuring another 10.
Los Angeles County Sheriff Robert Luna said the gunman, Huu Can Tran, carried a semi-automatic pistol with an extended magazine, and may have been carried out with the intent to kill more people at another dance hall.
However, two brave bystanders disarmed him, likely saving more lives.
Investigators are scrambling to establish why Tran carried out the attack before fatally turning the gun on himself hours later.
The Lunar New Year massacre carried out by 72-year-old Huu Can Tran on Saturday night at Star Ballroom Dance Studio in Monterey Park, California has left investigators scrambling to discover a motive for his actions.
While no other suspects are being sought, officials are trying to identify the 10 people he killed and seven people remain hospitalized.
Los Angeles County Sheriff Robert Luna described Tran as carrying a semi-automatic pistol with an extended magazine.
Tran, who had a history of misdemeanour arrests, then reportedly stormed into another "rival" dance hall, where he was disarmed by two community members who were commended as "heroes" by the Sheriff.
Luna said the reasons for his shooting remain elusive and that his rampage could have been far worse.
A second handgun was discovered in the van where Tran was found dead.