A mother in Takamatsu, Kagawa Prefecture, who was arrested after her two young daughters died of heatstroke had left them in a parked car while she went to at least three bars with a male friend for hours, sources said Saturday.

Maria Takeuchi, 26, was arrested Friday for allegedly leaving her daughters — Mayuri, 6, and Yurie, 3 — in a car for over 15 hours through early Thursday afternoon, when the children were found unresponsive. They were later pronounced dead at a hospital.

An autopsy found that the girls died of dehydration caused by heatstroke, the police said. The temperature rose to as high as 37.6 degrees Thursday in Takamatsu, a record for September.

Takeuchi allegedly left them in a passenger car at a parking lot in Takamatsu from around 9 p.m. Wednesday, resulting in their deaths, the police said, adding she is declining to speak about the allegations.

Her case was sent to prosecutors on Saturday.

After drinking until dawn Thursday, she moved the car and found the girls laying still on the rear seat. As she did not call for an ambulance until the afternoon, the police are investigating what she did during the intervening time.

When police officers and rescuers arrived at the scene, Takeuchi told them she had left the car for a period of two hours as she needed to go to the restroom for her chronic disease, the police said, adding that they believe she lied to avoid being arrested.

Inside the vehicle, there were half-empty bottles of water and a bag containing half-eaten bread, they said.