The 35-year-old woman and her 11-month-old daughter died after the grey Ford Focus they were in was involved in a collision with a yellow lorry on the A41 between Tern Hill and Newport.
Nobody else was hurt in the crash, which happened at around 1am on Tuesday.
West Mercia Police has now confirmed that the crash is being treated as murder and that the woman driving the car was the baby girl's mother.
Nobody has been arrested and no suspects are being searched for. However the force said it was not yet able to specify whether both the woman and her baby are believed to be victims.
A statement said: "Next of kin have been informed but formal identification has yet to take place.
"Officers are not looking to identify any suspects but are appealing for anyone with any information about the incident."
The crash, which happened near Lavender Cottage, was the second fatal collision in Shropshire in the space of three days.
The first crash involved two cars and happened in Lilleshall on Saturday evening. A woman driving one of the cars died at the scene and a 19-month-old girl who was a passenger in the other car died in hospital two days later.
West Midlands Ambulance Service said it sent multiple resources, including three ambulances and three doctors, to the A41 crash alongside police and firefighters.
A spokeswoman said: "The two occupants of the car - a woman and a young child - were in a critical condition.
"Crews worked quickly as a team to provide advanced trauma care with assistance from police and fire colleagues.
"Tragically, despite the best efforts of everyone, nothing could be done to save the woman and child and they were both confirmed deceased on scene.
"The driver of the HGV, a man, was assessed by ambulance staff but didn't require hospital treatment and was discharged on scene."
West Mercia Police has urged anyone who was in the area around the time of the incident or who may have captured the vehicles on dashcam footage to contact them.