The child was admitted for observation, but is in good condition.
The trooper was taking his 9-month-old and 4-year-old to daycare in his cruiser when it was broadsided by an SUV.
The accident happened just after 7:00 a.m. Monday at the intersection of McKennans Church Road and Mill Creek in Wilmington.
17-year-old Scott Jenkins of Wilmington was headed to high school with his friends when his 1994 Ford Bronco broadsided the marked state police car.
Police say an eastbound vehicle on Mill Creek Road began to make a right turn onto southbound McKennans Church Road but stopped after partially completing the turn, and the trooper began to turn left.
As the trooper was completing the turn onto southbound McKennans Church Road, Jenkins, who was traveling behind the stopped vehicle, continued straight through the intersection and struck the passenger side of the State Police car.
Inside the marked unit were a 38-year-old state trooper, who was behind the wheel, and his two children in the back, fastened into child car seats.
Authorities said the trooper, a detective assigned as a school resource officer and posted at Troop 2, was on his way to drop his children off at daycare. The Red Clay School District said he works at John Dickinson High School.
State police say troopers are allowed to transport their children if they are going from home to an assignment.
Jenkins taken by ambulance to A.I. duPont Hospital, where he was treated for minor injuries. Two 15-year-old passengers in his vehicle were not injured.
Police say the trooper's two children were also taken to A.I. duPont Hospital. The four-year-old was treated and released, but the 9-month-old remains hospitalized for observation.
The Trooper received minor injuries and did not require immediate medical treatment.
Police say everyone involved in the accident was wearing a seatbelt.
No charges have been filed. The investigation is continuing.