Three months after a quadruple homicide shocked the residents of Hayes Valley, the San Francisco Police Department says that they know who the killers are — but that they can't do anything to arrest the suspects without the public's help.

As you probably remember, on Friday, January 9 at about 10 p.m., as many as 15 shots were fired at four men in a 2005 Honda Civic near Page and Laguna Streets.

Four men, Yalani Chinyamurindi, 19, of San Francisco; Harith Atchan, 21, of San Francisco; David Saucier, 20, of Antioch; and Manuel O’Neal, 22, with no permanent city of residence, were pronounced dead at the scene.

Days after the shooting, police posted fliers asking for community help near the scene of the crime.

Posted all along Haight Street: @SFPD asking for tips re: Friday's quadruple homicide pic.twitter.com/jfD8C8f09F — Vivian Ho (@VivianHo) January 11, 2015

But it appears none was forthcoming, as this week a homicide cop is begging for the public's help to nab these shooters.

According to ABC7, "Police believe they know who the killers are. The are members of a Western Addition gang who may have ambushed the victims because they were on their turf."

However, no arrests have been made in the quadruple homicide because police "have no witnesses."

"That's all we're missing at this point. We, like I said, have a lot of physical evidence. We just need someone to come forward and let us know what they saw that night," SFPD Homicide Department Lt. Tony Chaplin told ABC7.

The case is described by police as "high priority," high enough in fact that "police say they have asked the mayor's office to approve a reward in this case and hope that will encourage witnesses to come forward."

Says San Francisco District Attorney's office spokesperson Alex Bastian, "whoever can help with the prosecution and the investigation of this case, really needs to step up and talk to the police department and provide that vital piece of evidence to make the arrest and prosecution in this case a reality."

But without that witness, the SFPD's hands are basically tied.

Know something? Call SFPD's anonymous tip line at 415-575-4444 or send a tip by text message to TIP411 with "SFPD" at the start of the message.

Previously: Four Men Killed In Hayes Valley Shooting

Vigil Tonight For Four Men Killed In Hayes Valley

Rental Car Used In Hayes Valley Drive-By Traced To Walnut Creek