A pair of votive candles and a cold cigar stub rested beside a utility box Tuesday morning at First Street and West Ruby Avenue in North Richmond.

The man behind the security gate of the corner unit knew nothing -- emphatically. Passers-by chuckled similar denials.

Nobody saw, heard or noticed anything about 9 p.m. Monday, when a car drove past a block away and someone inside opened fired on 18-year-old Oakland resident Raymone Boyd, killing him and sending a nearby woman to a hospital in critical condition.

"It's a bad neighborhood," explained one neighbor. "It's not safe. These guys see me talking and think, 'He knows too much. I'm going to kill him.' "

Contra Costa sheriff's deputies heard the shots and found the victims on the ground at 8:52 p.m. in this unincorporated neighborhood of Richmond. While investigating, they found a car nearby that investigators say the attackers likely used.

People ran from the vehicle and escaped, sheriff's Capt. Elise Warren said. Richmond police reported it carjacked on Nov. 11.

"That area has not been extremely active lately," Warren said. "But we have seen violence there. Right now we do not know the motive."

Meanwhile, the homicide prompted a sharp response from Richmond police, patrol deputies and others involved in stanching retaliatory attacks, including the city's Office of Neighborhood Safety and the local faith community.

"We are paying close attention to this shooting, because there is high potential for retaliatory violence," Richmond police Capt. Mark Gagan said.

Residents can expect many uniformed officers in the neighborhoods this week, Gagan added, part of an effort to minimize opportunities for attacks in the short term. As of Tuesday morning, neither agency reported any shootings likely related to the killing.

But attacks along this pot-holed road, running through a few short blocks of beige public housing, did catalyze some of the region's worst shooting sprees this year, investigators say.

A nonfatal shooting on West Ruby touched off a ping-pong of retaliatory gunfire between North Richmond and central Richmond gang factions in late August, wounding five. And a July 3 shooting on West Ruby killed a 28-year-old man, which police believe led to a retaliatory assault-weapon shooting that left a 30-year-old dead in the Iron Triangle neighborhood soon thereafter, and another man in his car thumbless.

The same night, somebody killed 19-year-old Rashad Bailey as he visited a cousin in south Richmond, dashing his father's hopes of bringing him into the family barber shop.

"What I can say is that there is an obvious, definite pattern of shootings between North and central Richmond," Gagan said. "It's a call to action for both of our police departments."

Contact Karl Fischer at 510-262-2728. Follow him at Twitter.com/kfischer510.