NEW DELHI, Feb. 13 (Xinhua) -- At least five people were killed and 15 others wounded Tuesday in a blast inside a vessel at a shipyard in southern Indian state of Kerala, officials said.

The blast took place at the Kochi shipyard in Ernakulam district, about 200 km north of Thiruvananthapuram, the capital city of Kerala.

"The blast went off on board a ship that was undergoing some repairs, killing five people and wounding several others," an official said.

"The blast triggered fire, following which firefighters were pressed in to contain the blaze."

Reports said 15 people wounded in the blast were immediately sent to a local hospital.

The ship belonged to India's state-owned oil and natural gas corporation, which was docked at the shipyard for repairs.

According to officials, the explosion took place at the water tank of the ship. However, the cause of the blast was not immediately known.

Rescue work was going on in the yard and firefighters were trying to contain the blaze amid columns of smoke emanating from the ship.

Unconfirmed reports said two people were trapped inside the ship.

Meanwhile, Kerala Chief Minister Pinarayi Vijayan has expressed grief over the killing of five people in the tragedy.

"The incident that led to the death of five people in Cochin Shipyard is sad," an official statement said. "Fire force and police have been instructed for intensive rescue operations," it added.