At least five people were killed and 15 others injured in an explosion onboard Sagar Bhushan, a vessel owned by the Oil and Natural Gas Corporation (ONGC), at the Cochin Shipyard on Tuesday. "All trapped inside the ship have been rescued," said Kochi city police commissioner M P Dinesh. Speaking to the media, the officer said: "The death toll from the blast includes some who apparently choked on the smoke after the explosion. "A probe has been ordered," Dinesh said. The exploratory drill ship of the public sector firm was berthed at the yard for repair and maintenance. The blast took place around 11 am in the water ballast of the berthed ONGC drillship Sagar Bhushan when some 20 workers were working in the tanker ship. Those working at the time of the blast mostly included daily laborers and contract workers. Tuesday being a holiday, no regular workers of the shipyard were present. Reports said there were two Keralites among the deceased. They were identified as Ramshad, a Vypin native, and Kevin, who hails from Pathanamthitta. Eight of those injured were admitted to the Medical Trust Hospital in the city, one is said to be critical. According to reports, the man has suffered 90 per cent burns. The police and the fire and rescue services were at the accident spot.