A sixth member of the Adelaide family involved in a fatal road crash in India has died, suffering a heart attack after he heard his two daughters and three grandchildren were killed in the accident.

Adelaide couple Rupendra and Anamika Datta were travelling with family in a hire car to the Taj Mahal last Sunday.

It is believed a burst tyre sent the car into a safety barrier, before the SUV flipped on its roof and landed in the path of oncoming traffic.

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Ms Datta, 45, her sister and two daughters died at the scene, and her teenage son died later in hospital. Mr Datta, 48, remains in hospital with critical injuries.

Flowers were laid outside the Datta family’s Urban India restaurant on Henley Beach Road. Photo: ABC

Anamika Datta’s father, who was also in the car, survived but has now died in hospital.

He suffered a heart attack after finding out the extent of the tragedy.

The family had been just days from returning home to Australia.

Back in Adelaide, other family and friends plan to gather at the Datta family’s Urban India restaurant at Mile End on Thursday evening for a Hindu prayer service.

A close family friend said Adelaide’s Indian community was in mourning over the tragedy.

Staff opened the Urban India restaurant this week despite the family tragedy, saying they wanted to press on to support Mr Datta.

They said it was their responsibility to open for business, as they prayed for his health.

One family friend said Mr Datta had suffered a spinal injury in the crash.

Another said he had been transferred from a first hospital to another in New Delhi.

The driver of the car involved in the accident also was taken to hospital for treatment of injuries.