An Indian naval submarine docked in Mumbai exploded early Wednesday. Officials said many of those on board the INS Sindhurakshak escaped by jumping over the side, the Indo-Asian News Service reported. But 18 sailors were feared trapped. Fire officials said the blaze on board the vessel was brought under control at about 3 a.m., almost 3 hours after it started. The submarine was in the Naval Dockyard, a high-security area. The cause of the explosion is under investigation.