Historically, several aircraft were designated bomber destroyers prior to and during the Second World War. They were a type of interceptor aircraft intended to destroy enemy bomber aircraft. Bomber destroyers were typically larger and heavier than general interceptors, designed to mount more powerful armament, and often having twin engines.[citation needed] They were a generally intended for day use, so were a separate category from the existing night fighters, although their characteristics overlapped heavily with night fighters, and with the concept of an interceptor in general.