SAN FRANCISCO -- A 21-year-old man is being held on three counts of murder related to a shooting in San Francisco's Excelsior District over the weekend that killed a father and two of his sons.

Eileen Hirst, a spokeswoman for the Sheriff's Department, says Edwin Ramos of El Sobrante is being held without bail in the San Francisco County Jail after being taken into custody for questioning at his home Wednesday. Authorities say Ramos denies he committed the murders. Police announced his arrest later that afternoon.

Police say Tony Bologna was driving home Sunday when he was forced to stop in an intersection, blocking the path of another car. Bologna backed up to allow the other driver through.

But someone from that car shot at Bologna's vehicle, killing him and his 20-year-old son Michael. Tony Bologna's youngest son, 16-year-old Matthew, was pronounced dead Tuesday after being taken off of life support.

"He has been booked for three counts of murder," police Chief Heather Fong said at a Wednesday evening press conference.

Fong offered condolences to the Bologna family and went on to praise the efforts of police detectives and the public in reporting some "helpful" tips, she said.

Other assistance came with the earlier arrest of an unidentified person who reportedly provided information that led to both Ramos' arrest, and the recovery of a vehicle "very similar" to the Chrysler 300 they believed to be involved with the shooting, according to police.

Homicide Inspector Brian Delahunty said he believed Ramos would admit that he is a gang member.

Police declined to elaborate further about the investigation, which is still ongoing. Anyone with information about the shooting is asked to call the San Francisco Police Department's homicide detail at (415) 553-1145 or the anonymous tip line at (415) 575-4444.

Earlier Wednesday, friends of the Bologna family held an emotional gathering at the Excelsior District intersection where the incident took place. A small memorial to the victims has been erected there.

"I went to school with them. I have no words for what happened. Just speechless," said stunned family friend Liz Ramos.

Ramos said she grew up with Tony Bologna's wife, Danielle, who arrived at the morning memorial in tears and only managed to stay for a few minutes.

"They were a good family. Danielle and Tony were very good parents. She loved her children dearly and they were a wonderful family and everyone is going to miss them very, very much," said another friend.

Bologna's brother-in-law Frank Kennedy told KTVU Channel 2 that the family set up a fund for the Bologna's two surviving children.

“This is really devastating. Something we will never recover from. We will have to move forward in life and hold the family together," said Kennedy.

Keith Myers was the elder Bologna's boss at Draeger's Market in San Mateo. The family run market also created a fund for the Bologna family Wednesday.

"He had a really excellent work ethic. He cared about his job, cared about the store. He just wasn't here to put in time and to get a paycheck. Really, the emphasis is on Anthony's family right now. That is the purpose behind this, pure and simple," explained Myers.