At least two people opened fire on a crowd watching a football game at a family gathering, the authorities said. No suspects have been identified.

Credit...Gary Kazanjian for The New York Times

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Four people were fatally shot and six others wounded after at least two people opened fire at a family gathering in Fresno, Calif., on Sunday, then fled, the authorities said.

No suspects had been identified as of Monday morning, and the police said they were collecting statements from witnesses and running shell casings through a national database. The motive and number of assailants were unknown.

About 30 friends and family members were at the gathering at a home in Fresno when the gunfire began, Andy Hall, the chief of the Fresno Police Department, said at a news conference on Monday. The authorities received reports of the shooting shortly before 8 p.m. local time.

Chief Hall said the gunmen, who were armed with pistols, entered the property through an unlocked gate and began firing at people who were watching football in the yard.

“They walked through the backyard and began immediately firing through the crowd,” he said. “The witnesses described only seeing flashes of light from the weapon, as it was too dark on that side of the house to see the suspects.”

He added that the party was “just a family event” and had been peaceful and quiet until that moment.

[Fearing a mass shooting, police officers in the Seattle area took a man’s guns. A judge gave them back.]

Late Monday, the authorities identified the four men killed as Xy Lee, 23, Phia Vang, 31, Kou Xiong, 38, and Kalaxang Thao, 40, all from Fresno. Mr. Xiong lived at house where the shooting occurred, officials said.

Michael Reid, a deputy chief of the police department, said that all 10 of the victims were Asian men, and added that several children were at the party.

“Thank God that no kids were hurt,” he said.

Mr. Reid said three of the men died in the yard, and one died after being taken to a nearby hospital. Six others were taken to hospitals with nonlife-threatening injuries, he said.

“This was not a random act,” Chief Hall said at the news conference on Monday. “It appears that this incident was a targeted act of violence against this residence. We are investigating leads, and we do have information that possibly some people at this party were involved in a disturbance earlier this week.”

He added that while the department was convening a task force to focus on Asian gangs in the area, there was no indication that the people at the party were affiliated with gangs.

Miguel Arias, the vice president of the Fresno City Council, said the people killed in the shooting were ethnic Hmong, members of a large community that arrived in Fresno as refugees from the wars in Laos and Vietnam starting in the 1970s.

“It’s heartbreaking for the Hmong community,” Mr. Arias said. “They came from a war-torn country and sought refuge here — and now they are now victims of this latest mass shooting.”

Pao Yang, the chief executive of the Fresno Center, a nonprofit community organization, said that two of the men who died were singers who were well known in the Hmong community.

Blong Xiong, a former City Council member in Fresno and a leader of the Hmong community, said the shooting came just as Hmong families in California were making plans to gather for the new year, which occurs at different times from October through December depending on the city. “We are supposed to be celebrating,” he said.

“This is senseless violence,” Mr. Reid said. “We’re going to do everything we can to find out who the perpetrators are and bring them to justice.”

The shooting occurred at 5361 East Lamona Avenue, just south of Fresno Yosemite International Airport. Videos posted on social media showed police cars and ambulances crowding a street lined with residential homes.

Fresno, a sprawling city of more than 500,000 people, is surrounded by vast expanses of almond and fruit trees. It is about 175 miles southeast of Sacramento.

California, which has some of the toughest gun laws in the nation, has had a rash of mass shootings in recent weeks.

On Thursday, a 16-year-old student killed two of his classmates and wounded three others in a shooting at a high school in Santa Clarita, Calif.

Two shootings at separate Halloween parties, one in a San Francisco suburb and another in Long Beach, south of Los Angeles, killed a total of eight people.

The shooting at an Airbnb rental in Orinda, the San Francisco suburb, appeared to involve rival gangs, David Livingston, the sheriff of Contra Costa County, said at a news briefing Friday. A total of 10 people were shot in what the sheriff called a “blood bath.”

Daniel Victor and Aimee Ortiz contributed reporting.