The shooting was reported at 12:12 p.m. at the intersection of Mission and 20th streets, according to police.
Investigators are still piecing together details about the case, and are hoping any witnesses at the busy intersection will call police with information that might lead to an arrest.
The shooting victim was taken to San Francisco General Hospital, where he was pronounced dead, according to police. Authorities have not yet released his name.
Police spokesman Sgt. Neville Gittens said today that investigators are considering the possibility the crime was gang-related, as the area is known as gang territory.
On Thursday evening at the same intersection, two people were stabbed and another shot with a BB gun. All three injuries were non-life threatening, and police have not positively linked that incident with today's shooting.
This afternoon, investigators were still at the scene, examining evidence on a bloodstained sidewalk surrounded by police tape, outside a Latino record shop.
An employee at the shop did not want to discuss the shooting, other than to say he suspected it was gang-related because there have been several other gang-related incidents in the area, he said.
Down the street, another shop worker said he heard one very loud gunshot and then ran to call police.
The man, who also declined to give his name out of concern for his safety -- "I have to work here," he murmured -- said there were crowds of people milling around the area when the shooting occurred.
"And amazingly, instead of running away from there, people were running into there," toward the man who was shot to look at what happened, he said, pointing at the crime scene, where crowds of onlookers still stood.
Before the shooting, a long line of people had gathered outside a nearby AT&T store to wait for the new iPhone, the man said.
"And in 10 seconds...they were all gone," and the store closed its doors, he said.
Anyone who may have witnessed the shooting, or with information about the case, is asked to call the Police Department's anonymous tip line at (415) 575-4444.
