MADRID (AP) — Autopsy results show the three members of British family who lost their lives in a swimming pool in southern Spain on Christmas eve died by drowning, police said Thursday.

Investigators were now trying to determine why they drowned, Civil Guard union spokesman officer Paco González said.

Leading Spanish newspaper El País said the autopsy results also showed none of the three had bruises or suffered intoxication.

The deaths of the 53-year-old father, his 9-year-old daughter and 16-year-old son occurred Tuesday in the Club La Costa World pool in the town of Mijas.

Spanish private news agency Europa Press said the girl got into difficulty first. Her brother and father then jumped into the pool and tried to save her but all three drowned.

Europa Press said the British family, including the children's mother and another child, were on vacation when the deaths occurred.

González said police inspected the pool and found no irregularities.

“(Police officers) did not find any anomaly that could indicate a swirl or a suctioning current,” he said.

Media reports said police initially suspected a problem in the pool"s suction system.

González said police found the girl’s swimming cap in a grate of the suction system.

He said the water in the pool was very cold and this may have been a factor in the drownings.

News reports said the pool was allowed to reopen Wednesday.