WEST ALLIS, Wis. -

Two boys have died in a duplex fire in the Milwaukee suburb of West Allis.

The Milwaukee Journal Sentinel reported three brothers and a friend were alone in the upper level of the duplex when it caught fire early Sunday. Two of the brothers survived, while one brother and a friend did not.

The boys who escaped were taken to Children's Hospital of Wisconsin in Wauwatosa but did not appear to be seriously hurt.

Police said the fire was reported shortly after 3:30 a.m.

The cause of the fire remains under investigation. Authorities have not released the names of the victims.