NRS 171.138: Breaking open door or window: Making arrest.

To make an arrest, a private person, if the offense is a felony, and in all cases a peace officer, may break open a door or window of the house, structure or other place of concealment in which the person to be arrested is, or in which there is reasonable grounds for believing the person to be, after having demanded admittance and explained the purpose for which admittance is desired.