Police are investigating an assault on a 16-year-old Healdsburg boy that left him with multiple stab wounds, apparently as the result of an attack by two male and two female aggressors.

The victim is expected to recover from his injuries, said police, who withheld his name to ensure his safety.

The attack is believed to have occurred at 8:36 p.m. Wednesday near Sunnyvale Drive and Lupine Road, not far from Gibbs Park, where witnesses reported seeing a lone male attacked by a group, authorities said. When police arrived, all involved had fled.

But at around 2:50 a.m. Thursday, emergency room personnel at Kaiser Permanente in Santa Rosa alerted Healdsburg police to a stabbing victim who said he was ambushed and assaulted.

Witnesses could only describe his assailants as two males and two females who appeared to be of high school age. One of the girls was with a dog.

They were last seen walking east on Sunnyvale Drive toward Poppy Hill Drive, police said.

Anyone with information about the case is asked to call Healdsburg police at 431-3377.