A sixth member of an 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.

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 what is believed to be a spinal injury.

Anamika Datta's father, NK Paliwal, who was also in the car, survived the accident but has now died in hospital.

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

Flowers were laid outside the Datta family's Urban India restaurant on Henley Beach Road. ( ABC News: Candice Marcus )

"When he heard that the whole family had passed away he had a cardiac arrest and died," family friend Anand Bhatia said.

"He passed away out of shock."

Mr Bhatia said he and others were working on how to get Mr Datta back to Australia for more medical treatment as soon as he was well enough to make the trip.

"The sad part is I don't know how Rupen will cope for the rest of his life, knowing his wife and children aren't there," he said.

Mr Bhatia said Rupen Datta's surgery had been successful and he was now conscious, but was not yet well enough to fly back to Adelaide.

The entire family had been just days away from returning home to Australia when the accident happened.

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.

Mr Bhatia said everyone was keen to "wish their souls to rest in peace".

He said Adelaide's entire Indian community was in mourning over the tragedy.

"It's a very big loss for us — a loving, very caring family," he said.

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.

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