YOUNG school students watched in horror as ambulance officers pulled a dead baby girl from a car parked outside St Thomas More's Catholic Primary School in Toowoomba yesterday afternoon.

The five-month-old baby girl had been left alone in the car on Ramsay Street while her mother picked up her other children from the primary school.

The distraught mother and a school staff member tried to resuscitate the baby at 3.30pm but could not revive her.

A Queensland Ambulance Service spokesman said the baby had been left in the car for a "very long time".

"It was beyond the reasonable normal time that you would leave a baby in the car," he said.

The screaming mother had to be escorted from the scene and ambulance officers took the baby's body to the Toowoomba Hospital to prevent upsetting passing students.

It is believed that the car's windows were wound up and that the car may have been locked.

Director of Catholic Education for the Diocese of Toowoomba John Borserio said the school community felt for the family.

"One of our staff members attempted to resuscitate the child but was unable to do so.

"They then took the appropriate steps and called the ambulance.

"I'm very proud of their work this afternoon and the work of the school.

"Our thoughts are with the family in this tragedy.

"Catholic Education is a close-knit community and any tragedy like this affects us all."

Counselling will be available to school staff and students today.

The Child Protection and Investigation Unit is investigating the circumstances of the death and a post-mortem examination will be conducted to determine the cause of death.