A gunman escaped after killing at least 10 people near Los Angeles, in one of the deadliest mass shootings in the US state of California.
Another 10 people were injured, some of them in critical condition.
The shooting took place in Monterey Park, which has a large Asian community, shortly after thousands of people had gathered for a festival to celebrate the Lunar New Year.
The gunman opened fire on a crowded dance studio in the downtown area.
Police officer Andrew Meyer said officers arrived at the scene at 22:22 local time on Saturday (06:22 GMT Sunday), finding people “running from the scene, screaming”.
Police said the victims were treated inside the Star Ballroom Dance studio and in the car park outside.
Police officers are searching for a suspect, aged between 30 and 50, who fled the scene, but have received varying descriptions of the attacker. The police are currently questioning dozens of witnesses.
“We need to get this individual off the street as quickly as possible,” Los Angeles County Sheriff Robert Luna said at a news conference Sunday.
He did not give details of the weapon used, but said the suspect may have fled in a white van. The motive behind the attack remains unclear.
Downtown Monterey Park, including West Garvey Street where the shooting took place, was decorated for the Lunar New Year celebration.
The celebration is one of the largest in California, drawing tens of thousands of people throughout the day.
Two days of festivities were planned, but officials canceled Sunday’s events after the shooting.
There is a heavy police presence in the city – which is about seven miles (11 km) east of downtown Los Angeles – and much of the area near the dance studio was closed off.
Police are investigating the possibility that the suspect entered another dance studio about 30 minutes after the attack.
Police said a person snatched the weapon he was carrying from the suspect at the Hambra dance studio. No one was injured at that site.
“We think there is an incident that may be related,” Luna said.
Chester Chong, president of the Chinese Chamber of Commerce in Los Angeles, told the BBC the attack stunned the community.
“This shouldn’t happen,” he said, adding that he was worried about his friend, the owner of the Star Ballroom Dance studio.
Others who were in the area at the time of the attack said they heard sounds they thought were fireworks. “I thought maybe it had something to do with the Lunar New Year,” Tony Lai, 35, told The Associated Press.
An eyewitness said that three people ran into his restaurant and told him to close the door as there was a man with a machine gun in the area.
A video clip circulating on social media showed police and firefighters rushing to an area on Garvey Street and treating victims.
The attack is one of the worst mass shootings in recent California history. The deadliest incident was in 1984, when a gunman killed 21 people at a McDonald’s branch in San Ysidro, near San Diego.
White House press secretary Karen Jean-Pierre said President Joe Biden, who has ordered the FBI to support local authorities, has been briefed.
Alhambra Mayor Sacha Rene Perez said the tragedy was “particularly painful”.
“Residents should celebrate with family, friends and loved ones, and not be afraid of armed violence.”
Meanwhile, California Governor Gavin Newsom described the shooting as a “horrific and cruel” act of gun violence and expressed sympathy for the victims.