A fire aboard a ferry in Indonesia's Java Sea has killed at least five people, with dozens more reported missing, according to officials. The vessel, named Mutiara Sentosa 2, was traveling from Surabaya, Indonesia's second-largest city in East Java, to Makassar in South Sulawesi when the blaze broke out. Rescue efforts are under way, and the missing include passengers and crew, though exact numbers have not been confirmed. The cause of the fire has not yet been determined. Authorities have not released further details about the victims or the condition of survivors. The Java Sea is a busy shipping route connecting major islands in the Indonesian archipelago, and ferry accidents are not uncommon in the region, though this incident has drawn particular attention due to the large number of people unaccounted for. Local agencies are coordinating search and rescue operations, and an investigation has been launched to determine how the fire started.