FRESNO, Calif. - A close-knit Hmong community was in shock after gunmen burst into a California backyard gathering and shot 10 men, killing four.

“We are right now just trying to figure out what to do, what are the next steps. How do we heal, how do we know what's going on,” said Bobby Bliatout, a community leader.

Sunday evening's attack killed Xy Lee, a Hmong singer and musician whose videos on YouTube have been viewed millions of times.

Also killed were Phia Vang, 31; Kou Xiong, 38; and Kalaxang Thao, 40, all of Fresno, according to the coroner's office. Three others remained hospitalized in serious condition, Community Regional Medical Center said in a statement.

Police have not determined a motive and no suspects were identified.

At a vigil Monday evening, relatives of Xiong set a table with photos, incense, and white candles outside the house.

Xiong is survived by a wife and young daughter, according to a GoFundMe page. It describes him as “a humble, kind, and caring individual who was always willing to help those in need.”

“Everybody is crying, our whole city is crying for these families,” said a sobbing Paula Yang, a friend of Xiong's brother.

Xiong's uncle, Neej Xiong, prayed on his hands and knees.

“It should've been me, not you,” Neej said. The Hmong are an ethnic group from Southeast Asia. Many fled after fighting alongside the United States during the Vietnam War.

There are about 300,000 Hmong living in the U.S., according to the 2017 American Community Survey by the U.S. Census. California has the nation's largest Hmong population and about 25,000 live in Fresno, comprising about 5% of the city's population of 525,000.

The gunmen targeted a house where about 16 men had gathered outside to watch football on television, police said. Women and children had already moved inside.

At least two men armed with semi-automatic handguns walked through a side gate and began firing randomly into the crowd before fleeing in the darkness, Police Chief Andrew Hall said.

The shooters did not speak. Witnesses saw only flashes when the pistols were fired, Hall said.

Police were investigating whether the shooting was connected to a recent disturbance involving some of the people at the party, Hall said. He did not describe the incident other than to say it occurred within the last week.

Women and children inside the house weren't hit, Hall said.

The chief said at least 60 officers were investigating along with the FBI, Homeland Security and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives.

While police hadn't found any gang connections to the victims, Hall also announced the establishment of an Asian gang task force over concerns about retaliation or more violence ahead of the Hmong New Year, which is celebrated next month.

There have been 11 violent incidents related to Asian gangs in the city this year, three in November, police said.

An Asian-American man was shot to death at a home earlier Sunday but police had not linked that killing to the party attack, Hall said.

“This is truly a good group of people who were simply having a party,” the chief said.

It was the third mass shooting in four days in California.

Last Thursday, a 16-year-old boy armed with a handgun killed two students and wounded three others at his high school in the Los Angeles suburb of Santa Clarita before killing himself.

On Saturday, a San Diego man killed his estranged wife and three of their sons before killing himself. A fourth son was on life-support.

There have been eight mass killings in California so far this year, claiming the lives of 33 people, according to a database compiled by The Associated Press, USA Today and Northeastern University. That's a dramatic increase from previous years, with eight mass killings for all of 2016-2018.

Rodriguez reported from San Francisco. Associated Press writer Stefanie Dazio in Los Angeles and news researcher Rhonda Shafner in New York also contributed to this report.