HAYWARD, Calif. -- Three people were injured in separate exchanges of gunfire, including one that involved a Hayward police officer, at a local shopping center Friday afternoon, a police captain said.

Shortly before 4 p.m., two Hayward police officers pulled into the parking lot of the shopping center at Santa Clara and Jackson streets to grab a meal, police Capt. Darryl McAllister said.

"Unbeknownst to them, they were pulling up and parking next to a shooting that was about to occur," McAllister said.

Two groups, each consisting of four to six young men, were involved in a conflict near where the officers parked, and as the officers exited their vehicle, members of the groups began shooting at each other, McAllister said.

The two groups then ran from the area, one traveling north and the other south.

McAllister said one of the members of the group that headed north noticed he was being followed by an officer, and turned on the officer. The officer fired at the suspect, who sustained an injury that does not appear to be life-threatening. McAllister did not know whether that suspect was armed.

Officers then detained him and located two other men who were shot. They were also detained and taken to local hospitals to be treated for non-life-threatening injuries.

Additional officers arrived and seven more people who were allegedly involved in the dispute were detained, McAllister said. He said police are investigating whether everyone involved in the initial shooting has been accounted for.

He said at least some members of both groups involved were armed.

"It's very fortunate that we had enough officers to respond that quickly ... in order to find and detain that many people who were involved," McAllister said.

He said he was "ecstatic" that no bystanders or officers were injured in the daytime shooting.

Police cordoned off the entire parking lot during the initial stage of the investigation.

Employees at some businesses inside the shopping center locked themselves inside their stores after learning about the shootings.

"One of the customers said there was a shooting. My manager ran in and locked the doors," said Pramodni Varma, a cashier and cook at Nation's Giant Hamburgers, 24999 Santa Clara St.

Varma said she did not see or hear gunfire, but said police told her to expect to remain locked down for another three to four hours.

Three employees at Radio Shack, 24901 Santa Clara St., also locked themselves inside their store. One employee described a hectic scene as "20 or more" police cruisers swarmed the parking lot "all at once" just after 4 p.m. No one at the store saw or heard the shootings, the employee said.