The gunman then crossed the street, got into his car, and shot and killed himself.
Police investigators, relatives and co-workers of the dentist, David Gong of San Francisco, were at a loss to understand why the 44-year-old patient killed him. They said the gunman, identified as Hailu Abje of San Francisco, had gum problems and had gone to Gong for treatment, but no one knew of any trouble between the two men.
Abje, an Ethiopian immigrant who was also known as Hailu Sudike, had no criminal record. Police said the only explanation they could come up with for why he opened fire at Jackson and Polk streets shortly before 8 a.m. was that he held Gong responsible for his dental problems.
"This guy's got really bad teeth and really bad gums," said Inspector Karen Lynch of the homicide detail. "I think he decided (Gong) was the source of the problem."
She added, however, that "there really was no sign he held a grudge in particular against this doctor. ... There was nothing out of the ordinary."
Lynch said Abje started seeing Gong eight years ago, but had not been to the dentist in the past year.
Witnesses told police that Abje walked up to Gong at 7:50 a.m. about a block from the medical building at 2000 Van Ness Ave. where the dentist had practiced for 26 years.
"You remember me?" the killer asked Gong, according to one witness, Nahum Selaya. The gunman then opened fire.
"The guy who was shot started running, then he fell on the ground, and the other guy shot him two times or more when he was on the ground," said Selaya, a janitor at the nearby Bell Tower restaurant.
After killing the dentist, Abje ran across Jackson Street, got into a blue Lincoln and shot himself to death.
A friend of Abje's, Kumsa Abdi, said he knew Abje to be generally friendly and happy. Abje drove a cab and parked cars, and sent money to relatives in Ethiopia, Abdi said.
"He had a problem with his teeth, but he had done something to fix his teeth," Abdi said. "His teeth were not good, but I didn't hear any complaint about it, not at all."
He said everyone who knew Abje was shocked by what he had done.
"Nobody expected him to do this, nobody," Abdi said. "He didn't have any problem with a dentist."
Gong's family said he was well-liked and would go out of his way to help troubled and poor people.
"We're just baffled," said Nel Leal, Gong's brother-in-law.
Gong's wife of 20 years, Erika Delacorte, said her husband had never told her of any problems he was having with a patient.
"He never mentioned anything about this guy," she said. "To me it is a completely unknown patient."
Delacorte said her husband took clients with mental problems. "He was extremely generous," she said. "His patients recognized that, even the very disturbed ones."
Police said they could find no evidence that the two men had clashed over dental service or anything else in the eight years they had a doctor-patient relationship.
Lynch said the dentist's office manager was "completely amazed and surprised -- nobody expected it to happen."
"It is very strange, and it's very sad," Lynch said. "This was a really decent guy. This dentist was really a good guy."
In addition to his wife, Gong leaves behind 19-year-old twin children, a son and daughter.
"He was devoted to his family, his interests and his hobbies," Leal said.
Gong was an avid sport fisherman and had traveled to New Zealand and the Caribbean. "It was just a hobby, but he took it quite seriously," Leal said.
Gong also enjoyed amateur astronomy and carpentry, and had built cabinets for his children's school and made other pieces of furniture for friends and family.