The child was injured on Wednesday on Aldine Westfield near the Hardy Toll Road in Montgomery County.
See also: Kids text 911 to report dad for alleged drinking, driving
Witnesses say they saw the child fall out of the front passenger seat of a moving vehicle. The man hit his brakes, jumping out the vehicle to help the child back into the front seat.
Deputies caught up with Matthew Killian a short time later, and found his two children inside the vehicle.
The child who fell out of the vehicle was transported to Texas Children's Hospital for treatment. Their condition is not known.
The other child who was in the vehicle was not injured.
Deputies with the Montgomery County Pct. 3 Constable's Office say Killian has three prior convictions for DWI. He is now facing three felony charges for this latest incident.
See also: Police; Drunk dad beat daycare owner for refusing to release kids
See also: Children tell 911 their dad was allegedly driving drunk