Four people were shot at a motorcycle bar in San Diego early Saturday, leading to a standoff between police and an armed suspect in the Mount Hope neighborhood. The incident, which was still unfolding at press time, came two weeks after nine people were killed and 18 injured in a massive shootout between five biker gangs outside the Twin Peaks restaurant in Waco, Texas.

The San Diego Police Department was called to the Chosen Few Motorcycle Club at 2:40 a.m. PDT Saturday after reports of shots fired inside the bar. Chosen Few is located about five miles from downtown San Diego. Patrons could be seen fleeing the building when police arrived, witnesses told local news outlets, though one man armed with a gun remained holed up inside. Those shot were transported to area hospitals where they are being treated for non-life threatening injuries, according to KGTV-TV in San Diego.

A SWAT team on the scene threw a flash-bang grenade into the bar and sent at least two remote controlled robots in before 9:30 a.m. PDT in an attempt to convince the suspect to surrender peacefully.

Law enforcement is investigating the motivation behind the shooting.

Biker groups throughout the country, fairly or not, are being looked at skeptically since nearly 200 gang members were arrested following the Waco shooting. Authorities say the Texas Confederation of Clubs and Independents, a group made up of a number of rival biker gangs, met at the Twin Peaks in Waco to discuss what authorities described as disagreements over turf, a claim denied by the gangs, who said the discussion revolved around motorcycle laws, according to Austin NBC affiliate KXAN-TV.

That incident, reportedly the product of long-simmering tension between Texas motorcycle groups, was enough convince restaurant and bar owners to re-consider serving bikers wearing gang vests. Others banned biker meetings, and canceled pre-planned motorcycle rallies.

The concern has even spread to Sturgis, South Dakota, home of the famous Sturgis Motorcycle Rally, which was attended by more than 400,000 bikers and enthusiasts last year. Ray Gold, founder of the One Eyed Jack’s Saloon in Sturgis, told the AP he will no longer serve beer to bikers wearing vests that indicate they are in a biker gang. “We don’t want gangs here because we lose good customers,” he said.  Rob Barnett, a biker and owner of the Deer Crossing Saloon in Selma, Texas, previously told IBTimes he would be banning confederation meetings following the Waco shootout. “I’ll help them out, but I’m a business before I’m a biker,” he told the AP.