Flashing lights atop speeding patrol cars mean that officers are heading to emergency calls. Officers also use these lights while their cars are parked for police incidents that are in progress---for example, a vehicle traffic stop or domestic disturbance at a residence. Approaching police lights warn civilians to move out of the way and to avoid police activity scenes. Each bright color is different and defines a certain situation.
Light bars have at least two colors. Red lights signify an immediate emergency. Blue lights define police presence and can be spotted easily from a great distance. White lights are used by night-shift officers to brighten dark areas or to shine on suspects who are traveling on foot or being interviewed. Yellow lights warn approaching vehicles that patrol cars are slowing down or parked on busy roads. All lights may be used at the same time.
In many departments, patrol car lights have base rotators, enabling the lights to turn at 360 degree angles so that glows spread in all directions. Some light bars are equipped with a strobe feature and a main LED light for a brighter presence.
During a routine traffic stop, the lights make commuters aware of parked vehicles along the roadside. At accident scenes, the purpose is to have approaching vehicles slow down or stop. For emergency travel or police chases, flashing lights warn vehicles and pedestrians to stay away. Officers can also use lights while double-parked or if they have to go inside a residence or business.
Additional Types of Lights
In unmarked police vehicles, interior lights are less evident to the public. For detectives or other plainclothes personnel, mini light bars are positioned behind the windshield or by the back window. For undercover officers, small portable lights are hidden until they need to be used for emergency activities. These globes are placed on the dashboard immediately before officers take off. Most patrol cars are equipped with small handle spotlights, close to the driver or passenger side mirror, in order for night patrol officers to point beams at suspicious-looking persons or dark buildings.
Although the sight of approaching lights can be startling, civilians can help officers get to emergency calls. Drivers should immediately pull over to the right side of the road and stop. Other vehicles and pedestrians should avoid intersections. If a lit-up patrol car is directly behind a vehicle, the driver should halt at a safe turn-off for an officer interview. All Code 3 calls---life-or-death emergencies---require officers to travel at high speeds with flashing lights and sirens. If a violent incident is in progress---for example, a bank robbery---sirens can remain silent. This tactic prevents criminals from fleeing before officers arrive.