By the time four city trucks were set ablaze next to Hemet City Hall last week, the police here had become familiar with their new life under siege.
A pipe bomb was found beneath an unmarked Hemet, Calif., police car on March 5 as it sat parked outside a convenience store.
The arson was the most recent episode during four months of threats of violence and attempted attacks against peace officers in the city that officials say are reprisals for crackdowns on local motorcycle gangs.
Now this city of tract homes and trailer parks in Riverside County, about 80 miles east of Los Angeles, is on edge, with barricades and an iron fence going up around the Police Department downtown, "to prevent someone from lobbing a grenade or something in the window," Police Chief Richard Dana said in an interview.
"We go around with a target painted on our backs," Chief Dana said Friday. "Now, an officer walks out from roll call, then gets on his knees to look under his car and see that there's no bomb there."
The Hemet Police Department, the state attorney general's office and federal agencies have raised a $200,000 reward for any information leading to an arrest and conviction in the attacks.
The trouble started for Hemet officials shortly after a gang task force began "putting pressure" on the Vagos motorcycle gang late last year by checking members for potential parole violations, said John Hall, a spokesman for the district attorney's office. "This group has parole violators and violent people," he said. "There's a history of bar fights, identity theft, drug sales."
On Dec. 31, someone used plastic tubing to reroute a natural gas pipeline to spew fumes into the headquarters of the county's gang task force unit in Hemet, Chief Dana said. Two officers entered the building, but smelled fumes and decided not to flip a light switch that might have ignited the building.
On Feb. 23, someone hooked a homemade gun to a gate outside the same building, rigging it to fire. One bullet whizzed past the head of an officer who tried to enter, missing him because the gate did not open fully.
On the morning of March 5, a crude pipe bomb was found strapped beneath an unmarked police car used by task force members as it sat parked outside a convenience store.
Just before sunrise on March 17, officers from local, state and federal agencies conducted a raid on Vagos members suspected of parole violations. Days later, a 911 caller threatened to blow up a patrol car within 48 hours "in retaliation for the raid," Mr. Hall said. No attack took place.
In January, the Hemet police said that they suspected members of Vagos, the largest motorcycle gang in the state, with 600 members, as being behind the gas line booby trap, but Chief Dana said that the investigation in that case had expanded to other groups as well.
The Riverside County District Attorney's office continued to focus on Vagos as a group with potential ties to the attacks, Mr. Hall said Friday.
"The Vagos are a typical violent gang," he said. "Vagos is a gang we've put pressure on. This was targeting gang task force members. Vagos has a history of trying to infiltrate and affect law enforcement operations."
Pat Palafox, the Vagos president, said there was "no connection between Vagos and any attacks."
He said those arrested during the March 17 raid "weren't current members of the club."
"Vagos is a brotherhood," said Mr. Palafox, 47. "We support each other. Like any organization, there are people off the grid. But Vagos get harassed by police more than any other motorcycle clubs, or any gangs around here."
The city of Hemet is about 27 square miles of flat streets and low buildings near the base of the San Jacinto Mountains, where land abutting the yellow hills is cheap compared with Los Angeles and San Diego.
"That brought young families," Chief Dana said, "but it also drew people wanting to take advantage."
A housing boom in the last decade nearly doubled the population to more than 100,000, he said.
The gang task force - an amalgam of the local police, sheriff's deputies and state and federal agencies - has used parole sweeps to monitor the county's mix of white supremacist groups and street and motorcycle gangs.
"Clearly, we irritated somebody somewhere along the line," Chief Dana said. "However, I would've done it anyway. I don't like gang members. I don't like them making people scared to go to the store."