Strange helicopters may hover over the Sonoma Raceway this week, with large electronic sensors mounted on their noses.

There may also be sounds of explosions might pummel the air, from both simulated gunfire and explosions, as well as loudspeaker-amplified voices barking instructions.

And a variety of military-looking vehicles could be ranging Highways 121 and 37 in the vicinity of the Sonoma Raceway, coming and going from the staging grounds for a multi-agency “all-risk drill” scheduled for this week just outside of Sonoma.

It will all be part of a terrorism and active shooter response drill, involving several emergency response agencies from Sonoma and Marin counties from Wednesday to Friday, March 21-23.

The majority of the drill activity will take place on Thursday, March 22, between the hours of 7 and 11:30 a.m. The drill is not for public viewing, but the Novato Fire District warns that traffic flow in the area near the Sonoma Raceway may be affected.

“The main message isn’t really about traffic, it is to notify folks that it is a drill and not real,” said Sandy Wargo of the Novato Fire District. “Some people might be mistaken and then text or tweet incorrect information.”

As well as the state National Guard’s Homeland Response Force, other participating agencies include the Governor’s Office of Emergency Services (Cal OES), FEMA Urban Assistance Team 7, the North Bay Incident Management Team (NBIMT), several Marin County fire districts and more.

The Sonoma Raceway’s large electronic sign should be announcing that a drill is in progress starting Wednesday morning.