The gang enforcement unit in the desert city of Hemet was on high alert Thursday after a bizarre booby trap sent a bullet whizzing past an officer in what authorities said was the second attack in two months at a building used by the task force.

The gang officer escaped injury Tuesday from the single shot triggered as he rolled up a booby-trapped security fence at the building, police spokesman Lt. Duane Wisehart said.

"It was obviously designed to kill or injure an officer, had it gone off exactly as intended," Wisehart said, calling the attack a form of domestic terrorism.

He described the device as a modified weapon designed to fire a single handgun-caliber bullet. The shot missed because the officer was standing to the side of the fence instead of in front of it as he pulled it open.

"It was nothing but luck the officer was not standing exactly where the person expected him," Wisehart said.

Hemet, a foreclosure-stricken city located in Riverside County's San Jacinto Valley with a population of about 75,000, has seen an upswing in gang membership in recent years.

On Dec. 31, someone drilled a hole in the roof of the gang task force building and diverted a natural gas line from a heater into the facility.

The line was discovered before anyone was hurt, even though an electrical spark - even from turning on a light switch - might have ignited the gas.

The device in Tuesday's incident was being examined. There was no video security footage of the building.

Wisehart said the gang unit was being moved to an undisclosed location and reviewing security measures.

"They're a little nervous," Wisehart said. "The guys are obviously becoming a lot more aware of their surroundings."

FBI spokeswoman Laura Eimiller said the Hemet Police Department was the lead agency investigating the attacks, though FBI agents were on hand to help if needed.