Officers are driving bait buses hoping to draw fire from the suspect or suspects.
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The agency is also getting help from the FBI.
"They're looking at damage on the bus and looking at what angle the projectile is coming from," CHP Golden Gate Division Commander Ernest Sanchez said.
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There have been 20 strikes in the past 45 days. Sanchez says they have a description of the vehicle they believe is involved in the attacks. They also have unmarked cars cruising the area between Woodside and Cupertino.
"They've damaged windows, they've dented the exterior of the vehicles," Sanchez said.
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A $10,000 reward is being offered for information leading to the arrest the person or people responsible.
The agency is asking for the public's help.
"What we're doing is alerting officers statewide, primarily in the Bay Area, during their interaction with the public to ask questions about something they may have seen traveling on the 280," Sanchez said.
"So the message is clear, if you're shooter out there, it's just a matter of time, we will catch you and prosecute you to the full extent of the law," Sanchez said.