(CNN) An American toddler fell to her death on Sunday from the deck of a Royal Caribbean cruise ship docked in San Juan, Puerto Rico, a spokesman for the local Port Authority said.

The 18-month-old girl was playing with her grandfather in a dining hall on deck 11 of the Freedom of the Seas , Port Authority spokesman José Carmona said. The dining area has large windows, and one pane was open.

The grandfather sat the girl in the window and lost his balance, and the girl fell to her death. "Sadly, she died on impact," Carmona said.

The ship was scheduled to depart for a weeklong voyage at 8:30 p.m. Sunday; the accidental fall happened about 5 p.m., according to Carmona. The girl's body was taken to a forensic unit in San Juan. Local police are still investigating the incident, which preliminarily has been determined to be an accident, Carmona said.

The family's attorney, Michael Winkleman, disputes this characterization of the incident. "I do think that there is going to be blame and significant blame on the cruise line," Winkleman told NBC News on Tuesday. He said that the toddler loved glass and windows, seeing through to the other side, and her grandfather had placed her on a ledge by a glass wall but had no idea one window within the wall was open.

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