A toddler who was rescued after being trapped for more than 14 hours inside a car that had plunged into a Utah river was in critical condition on Sunday, police said.

The 18-month-old girl was flown to hospital after she was discovered by a fisherman on Saturday, Spanish Fork Police Department Lieutenant Matt Johnson said. Her 25-year-old mother, who was the driver, died in the accident.

Police said the accident appears to have occurred at around 10:30 p.m. local time on Friday as the mother and her daughter were driving home to Springville, a suburb of Provo. A witness near the site heard a noise and investigated but observed nothing at the time, police said.

The car was discovered by a fisherman shortly after noon on Saturday, with the vehicle resting face-down in the water. When authorities arrived, they discovered the girl in her car seat, police said.

The car appears to have struck a cement barrier on a bridge before entering the river, police said, adding that the cause of the crash was not clear.

Authorities did not release the names of the girl and her mother, pending notification of their family.