OAKLAND -- A reputed gang member described by police as one of the city's "most dangerous fugitives" was arrested Thursday night after an off-duty Oakland officer spotted him dining in an upscale San Francisco restaurant, authorities said Friday.

Ronnie Flenaugh, 20, was arrested without incident about 10 p.m. Thursday at Ruth's Chris Steak House, 1601 Van Ness Ave., after he was seen by off-duty Officer Ernesto Leyva Jr., who was there celebrating his wife's birthday, police said.

Hours earlier in Las Vegas, Oakland police and Las Vegas officers had raided a house there believing Flenaugh might be there, but he was back in the Bay Area.

Oakland police Capt. Ersie Joyner III said Flenaugh and his gang are suspected of multiple killings, shootings, residential robberies and other crimes primarily in East Oakland. Oakland has worked with other agencies to find Flenaugh and put and end to the violence, police said.

Joyner said in his 21-year police career Flenaugh is one of the most violent and dangerous people he has dealt with and that Chief of Police Howard Jordan made him the highest priority for arrest.

Some of the shootings prompted retaliatory acts in which innocent people were injured, Joyner said, adding that in some of the shootings, more than 100 shots were fired causing "unnecessary danger" to the community.

Joyner disclosed that Flenaugh's girlfriend was seriously injured in one shooting that happened outside a school several months ago.

Investigators have been building cases against Flenaugh and expect to present evidence to prosecutors soon. He presently is charged with brandishing a firearm in an incident in East Oakland. He was arrested on that case Sept. 12, quickly made bail and after failing to appear in court, a no-bail warrant was issued for his arrest.

Joyner said Leyva and his wife were having dinner when Leyva, who is part of a team of officers who had been seeking Flenaugh, saw him and several other people come into the restaurant "trying to hide his identification" by wearing a hooded sweatshirt and a baseball cap pulled down on his head. But Leyva determined it was him and made a phone call to Oakland officers for assistance rather than risk violence in the restaurant. Flenaugh was arrested by Oakland and San Francisco police leaving the restaurant.

Joyner, who took part in the arrest, said he paid for Leyva and his wife's dinner "for the great job he did."

Some of the people with Flenaugh tried to leave without paying their bill, but officers made them go back and pay, police said.

Joyner said he hopes that Flenaugh's arrest will "send a message" to violent street gangs that "we are focusing on them" and that "we are taking crime fighting very seriously in our community."