(CNN) -- Authorities in California's Riverside County are investigating an early Monday morning fire at a building containing evidence collected by local police. Officials are calling the fire in the city of Hemet "suspicious" and investigating it as arson, according to a statement from the Hemet police department.
The incident "considered as connected to ... previous attacks on the City of Hemet Police (Department) in the last six months," the statement noted.
The fire occurred a little over three months after authorities offered a $200,000 reward for information on a string of attempts to kill members of a local gang task force.
Authorities have said they believe the close timing and identical targets of the attacks indicate they could be related.
On December 31, 2009, the unmarked headquarters of the Hemet Gang Task Force was targeted by someone who redirected the natural gas line on the roof into the building, filling up the office with deadly gas. Two task force members entering the office smelled gas and backed away before flipping the light switch and potentially causing the building to explode.
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.
On March 5, 2010, 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 Hemet police department 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 countywide.
As the county expanded and its population grew, so did the presence and reach of organized crime, according to John Hall, a spokeman for the Riverside district attorney's office.
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 members countywide.
It's possible that the gang members are feeling threatened (by the task force), that we're starting to impede on their activity and they're retaliating," Hall said in March. "It's reasonable to believe that they are targeting members of the task force specifically."
CNN's Brett Roegiers and Emanuella Grinberg contributed to this report