Ten men were shot, four of them fatally, during what police say was "very likely" a targeted shooting at a backyard football watch party in Fresno, California, on Sunday night.

Police say some 35 to 40 family and friends were watching a football game in the southeast of the city when one or more people sneaked onto the property through a side access and began shooting. They did not appear to have actually entered the house, Fresno Police Deputy Chief Michael Reed told reporters.

"Luckily, most of the women and children were inside," he said.

Some of the survivors initially listed in critical condition were now in stable condition, according to police.

Three people — all Asian men between the ages of 25 and 30 — died on the scene, Reed said during an overnight press conference. A fourth man died later at hospital. All those shot were between 25 and 35.

"It’s very likely that it was targeted — we just don’t know why," he said. "Somebody picked that house and came up and shot several times on the backside of it. It looks like there was a target."

Earlier, Lt. Bill Dooley said no suspect or suspects had been identified in the shooting, which was reported shortly before 8 p.m.

Police were canvassing the neighborhood to discover the motives for the shooting and who was behind it, Reed added.