What happens when a cop flashes his headlights at you?
What happens when a cop flashes his headlights at you? Technically it's just a matter of quickly getting your attention, debris in the road, wildlife or other hazards. If it's the emergency overhead lights, chances are their telling you to slow down.
What does it mean when a cop has lights but no siren?
If the lights are on but there is no siren, it could be that there is an ongoing crime and officers do not yet wish to alert the perpetrator of their presence. Another possibility is that, though an officer is headed to an emergency, there is no traffic on the road that needs to move out of the way.