Four men were killed and six others wounded in a shooting Sunday night at a house party in Fresno, California, police said. Fresno Police Chief Andrew Hall said at least two suspects sneaked though an unlocked gate into a football viewing party in the house's backyard and opened fire before fleeing on foot.

"This was not a random act," Hall said at a news conference Monday. "It appears that this incident was a targeted act of violence against this residence." The chief said several people at the party were involved in a recent disturbance, and police were looking into whether that incident was connected to the shooting.

There were about 30 people at the party, he said. Ten men were shot; three of then died at the scene and another died in surgery.

Emergency officials at the scene of what police called a "mass casualty" shooting in Fresno, California the night of November 17, 2019 KGPE-TV

Of the six wounded victims, only two were still in a hospital, and they were in stable condition as of late Monday morning, Hall said. All of the children at the party were inside the house at the time of the shooting.

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Hall only identified the victims by their age and gender: a 23-year-old man, a 31-year-old man, a 38-year-old man and a 40-year-old man. Police had earlier said the victims were Asian, and a community member said at the press conference two of the victims were well-known in the local Hmong community.

Police didn't know the suspects' ethnicity, Hall said, adding that witnesses only described seeing flashes of light as the shots were fired. Police haven't been able to rule out whether the shooting was related to gang violence.

The suspects were armed with what appeared to be semiautomatic pistols, Hall said. Investigators were going door to door looking for security cameras in the neighborhood, he said.

The Sacramento Bee reported the shooting was at least the second fatal gun attack in Fresno Sunday. A man in his 20s was shot dead early in the day. Police didn't say whether the incidents could be connected.