Police said they held grave fears for the woman after the incident which happened about 8am near the corner of Taylor Road and Midland Highway.

The road was busy at the time and witnesses stopped to help. Moorabool police local area commander Brendan McCrory said the woman had pulled off the road as she was driving.

“A 64-year-old female has had a medical episode just out of Meredith, witnesses have gone to her assistance when the car has driven into trees.

“She’s now in a critical condition in Geelong hospital.

“At this stage, from witness accounts, it’s definitely a medical episode and we have great concern for her health.”

It was a busy 24-hours for emergency crews with crashes throughout the day and night. 

On Monday afternoon, a man in his 20s survived a rollover on the Colac-Ballarat Road at Enfield.

The man was taken to Ballarat Base Hospital in a stable condition with shoulder and neck injuries.

Meanwhile, a teenage boy also escaped serious injury in a crash at Scarsdale early on Tuesday morning. Paramedics attended the smash at Scarsdale-Pitfield Road and the Glenelg Highway at midnight after a car crashed into a tree in a paddock.

The teen was taken to Ballarat Base Hospital, before being transferred to Royal Melbourne Hospital with leg injuries. He was also listed as being in a stable condition.

And in a separate incident another male teen was taken to hospital with leg injuries after being hit by a car in Smythes Creek just after 5.30pm on Monday night

He was taken to Ballarat Base Hospital in a stable condition.

Emergency services were also called out to a crash at the corner of Werona-Kingston Road and Daylesford-Clunes Road south of Smeaton at 11am after a car crashed into a pole. 

A man in his 20s was taken to Ballarat base hospital with suspected chest injuries in a stable condition.