The corrections officers were out jogging after work next to the county complex on 93 Avenue in Crown Point around 7 p.m. when they were hit by a vehicle. The driver did not stop.
The corrections officer who was killed was a veteran officer. Her family was being notified late Tuesday night.
One officer was being airlifted to Indianapolis for treatment. Two other officers are in the hospital.
The vehicle was described by one of the victims as a late model dark SUV.
One of the injured male officers is the son of the Lake County deputy chief.
Lake County Sheriff John Buncich is asking anyone who may have information or may have seen anything to help them find the driver.
"We have our medical team and our chaplaincy team is here. So we are dealing with it the best we can," said Buncich.