(CNN) -- Police in California say that with the arrests of 23 people this week, they are getting closer to those responsible for a string of brazen attacks against officers in a gang task force.
The booby trap-style attacks believed to be targeting the Hemet Police Department began in December when, police say, a natural gas line was rerouted into the task force's headquarters, risking an explosion. The most recent incident occurred in March, when four city code enforcement trucks were set ablaze in the Hemet City Hall parking lot.
None of the 23 suspects arrested Tuesday face charges directly related to the four attacks, but police are hopeful that they will lead them to the people responsible, Hemet Police Capt. Dave Brown told CNN.
"Tuesday's operation produced an enormous amount of property and evidence. The 23 people arrested were detained and interviewed, producing leads, and those leads are being followed up," Brown said.
The suspects were arrested throughout Riverside County on a variety of felony and misdemeanor charges -- from possession of weapons and stolen property to outstanding warrants and narcotics. Local and state law enforcement agencies participated in the raids, in which 35 locations were searched and evidence, including 16 weapons, was seized.
Some of those arrested have gang affiliations, Brown said, but it's still unclear whether the attacks are gang-related. A motive is still not known.
"Motive has been a missing piece, but once the suspects are identified, we believe a motive will follow," he said.
"Sometimes, in gang cases, the motive is clear from the beginning. But in this case, we're not even sure it's a gang case, and if so, we're not sure if one gang is operating independent of others or if there's some sort of cooperation between the gangs."
Hemet is one of eight local, state and federal agencies that make up the Riverside County Gang Task Force, which was formed in 2006 to address the growth of criminal street gangs and outlaw motorcycle gangs.
As the county expanded and its population grew, so did the presence and reach of organized crime. Since 1997, the number of gangs in Riverside County has grown from 266 to 391, according to the task force's website, and total gang membership has grown to 10,620 people countywide.
Authorities believe the attacks could be related because of their close timing and identical targets, John Hall, a spokesman for the district attorney's office, said last month.
On New Years Eve, the unmarked headquarters of the Hemet Gang Task Force was filled with deadly natural gas. Two task force members detected the gas, backed away and reported it.
On February 23, a task force member at the Hemet headquarters opened a security gate outside the building, which launched a homemade zip gun attached to the gate. The weapon fired, missing the officer's head by inches.
The headquarters has since been moved to an undisclosed location, where extra security precautions are being taken, Hall said.
On March 5, criminals targeted a task force member who had parked an unmarked police car in front of a convenience store in Hemet. The officer found what appeared to be a homemade pipe bomb hidden underneath the vehicle.
The attacks have drawn the attention of state and federal law enforcement, which have contributed manpower and money to a $200,000 reward offered in the case.
The Hemet Police Department has set up a confidential tip line for anyone with information: 951-765-3897. People can also e-mail tip to: firstname.lastname@example.org.