The California Highway Patrol is using decoy buses in an attempt to catch the people responsible for shooting metal pellets at the charter buses that Apple and Google employees use, as reported by Fortune.

Since January, there have been 20 reported shootings at the company charter buses, with the weapon thought to be a BB gun. While no one has been injured, CHP Golden Gate division commander Ernest Sanchez tells ABC7 that “[The shooter has] damaged windows, they’ve dented the exterior of the vehicles.”

In an effort to try to catch the suspect(s) behind the attacks, CHP is using decoy buses on Interstate 280, which will have undercover CHP investigators posing as riders. The hope, Sanchez says, is that if the decoy buses are also attacked the agency can “[look] at damage on the bus and [look] at what angle the projectile is coming from.”

The CHP says it has a description of the vehicle it believes is involved in the shootings. It has solicited help from the FBI, and the company that owns the buses, Storer, is offering a $10,000 reward for any information that leads to the arrest of any of the people responsible. The CHP has not disclosed possible motivations behind the attacks, though the growth of Silicon Valley companies has contributed gentrification in the area, causing spikes in rental prices and cost of living.