Del. Code tit. 21 § 4356A
Any motor vehicle used by a fire department or police department, emergency vehicles of state, federal, county or municipal departments, or public service corporations as are designated or authorized as emergency vehicles by the Secretary of Safety and Homeland Security, and state owned and operated snow removal equipment and vehicles, may be equipped with a green revolving or flashing light for use only when the vehicle is in service at an accident, fire or disaster scene to signify a command post to which fire and police officials may report for instructions or orders, or for use on hazardous material response vehicles traveling to such scene on the request of the fire department or the police department, or for use on state owned and operated snow removal equipment and vehicles during winter weather operations. Such green revolving or flashing lights may only be used on a vehicle for the purposes and in the manner stated in this section.
21 Del. C. § 4356A