(CNN) A group of family and friends were gathered in a backyard Sunday to watch a football game when two gunmen sneaked into the yard and began shooting, killing four young men and wounding six others, police in Fresno, California, said.

The Fresno Police Department is concerned someone might now seek to retaliate and is establishing an Asian gang task force that will aim to snuff out any further violence, Police Chief Andrew Hall said. Though he said he could not confirm the shooting was gang-related, he said his investigators weren't ruling it out.

About 30 people, including several children who were inside the home, were attending the party when the suspects -- who remain on the loose -- began shooting into the crowd, according to police.

About 16 partygoers, all of them men, were in the backyard watching the Sunday Night Football game when the gunfire erupted, Hall said. The party was peaceful and not "out of control in any way. It was just a family event," Hall 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 said.

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