The known number of lives lost in the grounding of the Italian cruise ship Costa Concordia has risen to 13 after divers removed the body of a woman from the stern of the capsized vessel Sunday.

On Saturday, the body of another woman was retrieved. Both women were said to be wearing life vests. They, along with most of the other victims of the January 13 disaster, have not been identified.

Nineteen people – most of them passengers – are still listed as missing. There is also concern that some unregistered passengers may have been on board.

The huge ship has been slowly shifting on the reef where it is resting off the Italian island of Giglio, causing concern and making the recovery efforts more difficult. There is also concern that the nearly 2,500 tons of fuel on board could start spilling into the sea, raising the possibility of an environmental disaster.

On Saturday Italian authorities declared a state of emergency on the small island.

The captain of the cruise ship, Francesco Schettino, remains under house arrest, accused of manslaughter and abandoning the vessel.