TOPEKA, Kan. (AP) — A 3-year-old brother and sister died after they spent more than two hours in a sweltering car parked in the driveway of the family home, investigators said Monday.

The temperature was about 75 degrees when the children were found Sunday afternoon, two hours after they were reported missing, authorities said. Shawnee County Sheriff's Sgt. Akim Reynolds said the temperature inside a car with its windows up could have reached 20 to 30 degrees warmer.

The mother was being questioned by detectives.

Authorities also were trying to determine how the children ended up in the car, Sheriff's Sgt. Jay Simecka said.