SAN FRANCISCO -- Police and residents in San Francisco's Outer Mission neighborhood were on edge after SFPD investigators identified a man killed in the area as the president of the San Francisco branch of the Hells Angels motorcycle club.

The victim, 46-year-old Mark Guardado, was shot at about 10:30 p.m. outside a bar at 24th Street and Treat Avenue in the city's Mission District, police said.

Authorities said Guardado was recently in Sonoma County court, facing felony charges in connection to an altercation in Petaluma last February.

On the evening of February 10, Guardado and the vice president of the Sonoma County chapter of the Hells Angels, 31-year-old Jonathon Nelson, got into a fight in Petaluma with a patron at McNear's Saloon & Dining House, Petaluma police Sgt. Jim Stephenson said.

The patron was knocked out in the fight, Stephenson said.

Guardado and Nelson were arrested at the scene on charges of assault with great bodily injury, assault with a deadly weapon and gang enhancements, Stephenson said.

Both men were later released on bail, but Petaluma police seized Guardado's Hells Angels jacket with his president's patch sewn on, and still have possession of the jacket, Stephenson said.

Police were investigating reports that Guardado was shot by a member of The Mongols, a rival motorcycle club. The Mongols are based in Southern California, but there are local chapters in Modesto and San Jose, authorities said.

The Mongols and the Hells Angels clashed six years ago at Harrah's Casino in Laughlin, Nevada. The incident left three people dead.

In response to Tuesday night's fatal shooting, there's been a heavy police presence as officers blanket the area. Police say they will continue to patrol the area in an effort to reassure residents they will remain safe despite worries of a possible war between the two motorcycle clubs.

"We are going to try and maintain a continued effort in this area with multiple means, uniformed officers, plain-clothed officers, specialized units that we have out here tonight," San Francisco Capt. Steve Tacchini told KTVU. "We are going to try and keep as much police presence in the neighborhood as possible."

Residents of the Mission District tell KTVU they will remain on edge until the case is solved.

"I'm afraid some young children will accidentally get shot in the crossfire," said local resident Rita Alviar, who works with the Mission Education Project. "I'm praying that this stops in our community."