WILLEMSTAD, Curacao (AP) — Authorities on the southern Caribbean island of Curacao are investigating the deaths of six-year-old twin girls found in a bathtub at a beach resort, a public prosecutor said yesterday.

Prosecutor Ludmila Vicento said the dead girls' Belgian mother is being evaluated by doctors at a psychiatric hospital, where she has been held since late Sunday. She said the 35-year-old woman has not been charged with anything.

Authorities on the Dutch Caribbean island are only identifying the mother by her initials, SV.

Vicento said witnesses at the Curacao Marriott Beach Resort & Emerald Casino saw the woman walk naked into the sea Sunday night. They brought her back to shore and called authorities.

Police soon found the lifeless girls in her room's tub. They have not released more details citing an ongoing probe. Autopsies on the children are pending.

The girls' grandmother was staying in a separate room from the woman and her twin daughters, according to Vicento. The children's father did not accompany them on their trip to Curacao, she added.

A spokeswoman for Marriott International said the company will do all it can to assist Curacao police in their investigation at the 237-room hotel.

"Our thoughts and prayers go out to the family and loved ones of the girls," Marriott spokeswoman Laura Botelho said in an email.