A gunman fatally shot a couple in their pickup truck, forcing their blood-spattered 5-year-old son to leave his baby sister and wander the neighborhood in search of help.

Police have made no arrests in the slayings, but have said the couple apparently knew their killer, who was seen by neighbors fleeing on foot from the scene.

Jose Antonio Delacruz, 31, and Flor Guzman-Vasquez, 28, both of Daly City, were found dead Friday night in the city's Mission Terrace neighborhood. The couple's 5-year-old son, Oscar Limon, and 13-month-old daughter, Sahian Michelle, were unhurt.

Mary Jo Cooney found the boy on her doorstep spattered with his parents' blood and clutching a Nintendo video game after the shooting. "'A bad man, he's trying to hurt my family' -- those were his exact words," Cooney said.

Relatives who gathered Monday to mourn the deaths said they had no idea why anyone would want to kill the couple, who were immigrants from the Mexican state of Jalisco.