Cannot speak for Thailand, but in the USA......
police cars, are authorized to disregard traffic control devices, including red lights, when they are responding to an emergency. This is outlined in various state statutes, which typically require that the vehicle's lights (usually red or blue or a combination) and sirens are in use to alert other road users of their approach.
Due Regard: However, this permission comes with the caveat that drivers of emergency vehicles must proceed with "due regard" for the safety of all persons using the highway. This means that even when running a red light, they must ensure it is safe to do so, taking into account other traffic, pedestrians, and the immediacy of the emergency.