BERLIN (AP) — Austrian police say two young girls have died after a driver slammed into the trailer they were being pulled in behind their mother's electric moped.

Police say a 1-year-old died at the scene of the accident on a rural highway near the town of Hausleiten, northwest of Vienna, before dusk Sunday evening. They say her 4-year-old sister died in a Vienna hospital overnight.

Police are investigating what caused the 60-year-old car driver to slam into the bicycle-type trailer, which is permitted on the slow-speed moped, knocking it 15 meters (yards) off the road into a field.

They say a blood-alcohol test indicated he was well below the legal limit.

The 39-year-old mother of the girls was injured and is being treated in a hospital. The driver and his wife were unharmed.