LOS ANGELES — Four people were shot dead and ten others wounded while watching a football game in the backyard of a central California home on Sunday, police said.

Police were called to the scene after at least one person opened fire into a crowd of about 35 people gathered outside the house in Fresno, around 200 miles (320 km) north of Los Angeles.

"Three people died on scene," Fresno deputy police chief Michael Reed told reporters, adding that a fourth was rushed to hospital in critical condition and succumbed to his injuries there.

All four of the dead and the ten treated for "non life-threatening" gunshot wounds were men aged between 25 and 35, Reed said.

"Our heart goes out to the families of the victims... this is senseless violence, he added.

"We are doing everything we can to bring the perpetrators to justice."

Reed said it was unclear how many perpetrators had been involved in the shooting and that there was "no indication" the incident was gang-related.

Police spokesman Bill Dooley said officers were looking for surveillance footage and witnesses to track the suspects.

He said the victims were a group of family and friends who had gathered at the residence to watch a football match.

Fresno councilor Luis Chavez, who represents the district where the shooting took place, said the incident was "not a reflection of our community."

"Our officers are working diligently to piece together the sequence of events that led up to this, but more importantly to bring all those involved to justice," he said, in comments reported by the Fresno Bee newspaper.

Shootings are a frequent occurrence in the United States, but despite the scale of the gun violence problem in the country, efforts to address it legislatively have long been largely deadlocked at the federal level.

Choua Vang, who lives near the site of Sunday's attack, said that Sunday's incident was the second shooting in the area in as many weeks.

"It makes me feel unsafe to be outside when the sun's down," he told the Fresno Bee.

Three days before Sunday's attack, a teenager gunned down two classmates at a high school in suburban Los Angeles before turning the weapon on himself.

The shooter died in a hospital one day later, leaving detectives baffled at the apparent lack of motive for the crime.

In July, a 19-year-old gunman opened fire at a food festival in Gilroy, several hours drive west of Fresno, killing three people. — AFP