The shooting happened near Eighth Lane and Linden Avenue at about 7:15 p.m. on Dec. 22.

Two victims, Omar Cortez, 18 and Gonzalo Avalos, 19, died at the scene. A third victim, Hector Flores, 20, was taken to San Francisco General where he died on Thursday.

Three other males between 15 and 20 years old were wounded and taken to San Francisco General Hospital. They are expected to survive.

Witnesses told police they saw three males in their late teens or early 20s driving away from scene in a dark-colored early 2000s-model Chevrolet Impala with tinted windows. The killings are being investigated as gang-related.

South San Francisco police spokeswoman Sgt. Joni Lee said today that the three survivors have not been cooperative with investigators and that few witnesses come forward.

"We're still investigating and going door to door looking for witnesses," Lee said.

South San Francisco Mayor Kevin Mullin said the Police Department has stepped up patrols in the neighborhood and investigators are aggressively pursuing all leads.

"But we need neighborhood members to come forward with any information that can be helpful," Mullin said.

Mullin said that in an effort to calm the violence and create a more stable neighborhood, the city plans to put together a coalition of city representatives, local nonprofits, school administrators and leaders from the area that has been impacted by the violence.

"The city is taking the lead on putting together a working group to develop a neighborhood-level outreach plan to better engage the community," Mullin said.

"It won't be easy and it will take time to develop," he said.

South San Francisco City Councilwoman Karyl Matsumoto emphasized the need for community engagement as the city takes steps to combat gun and gang violence.

"Nobody wants to see people killed, but we can't do it by ourselves," Matsumoto said.

"It takes more that the council and the school district. It takes the entire community," she said.