Emergency vehicles are specially designed vehicles allowed by law to respond to an emergency. They can include specialty trucks, police vehicles, fire trucks, ambulances, park ranger vehicles, tow trucks, or lifeguard vehicles, and as a rule, have light signals and sound to alert the public when moving to an emergency. Emergency vehicles are used by the police, hospital staff, rescue workers, volunteers, crime patrol during an emergency call and may move at high speed. They are not for public or commercial use but can carry people in need of help and equipment used in emergencies.