India's Prime Minister Narendra Modi has called Malcolm Turnbull to express his concern over the burning death of Punjabi native Manmeet Alisher.
Mr Alisher, 29, was burned alive when an "incendiary device" was thrown at him while he was letting passengers on at Moorooka on Friday morning.
The Guardian reported Mr Modi called Mr Turnbull to express the “sense of concern being felt in India” over Mr Alisher's death, particularly in light of the racially-motivated attacks on Indian students in 2009.
Mr Alisher's family are still to tell his elderly parents that he has died.
His mother is a heart patient and his father is elderly, and the family has decided to wait until they return his body to India to tell them.
"We have just said there was an accident, he's in a coma," a family spokesman told reporters.
"When we take the body to India, then we will break the news."
Mr Alisher's distraught brother Amit flew into Brisbane on Sunday and faced the media, but was too upset to speak.
Mr Alisher, a prominent figure and beloved singer in the Punjabi community, was employed as a casual bus driver and had only been working in the job for several months before Friday's horrific attack.
Anthony O'Donohue, 48, has been charged with murder, arson and 11 counts of attempted murder, and will remain in custody until his case returns to court in late November.
Health Minister Cameron Dick said O'Donohue had previously received public mental health services.
"I have requested the Director-General of Queensland Health to commission an independent investigation under the Hospital and Health Board Act 2011 regarding treatment provided to the accused," Mr Dick said in a statement on Monday.
Queensland Police Commissioner Ian Stewart said there was nothing to suggest the attack was racially motivated, but Mr Alisher's brother told the ABC he fears otherwise.
"We suspect that it may be (racially motivated)," Amit Alisher said.
"We would like to see due process, we have faith in the Australian system."
'A short yet meaningful life'
Manmeet Sharma hailed from Alisher, a small town near Lehragaga in Sangrur Dist of Punjab, India. He had been living in Brisbane over the last few years, according to Brisbane's Punjabi community.
Relative and friend Aman Bhangu told SBS Punjabi Radio he was an "outgoing, lively person who enjoyed his short yet meaningful life. He will surely be remembered for his beautiful smile and the work he did for social causes.”
He was popular within the Punjabi community in Australia as a singer. It was also understood he had a passion for poetry and singing.
Preet Siyan a local Punjabi singer who shared the stage with him, described him as “a man with heart.
"It is a big loss to family friends and the local community. He was a great poet and singer. He will be dearly missed.”
While Gurjant, a Punjabi community member, said Mr Alisher was "such a lively, vivacious, intelligent man".
Local councillor Steve Griffiths posted a message on his Facebook page, saying the vigil was not only to pay respect to Mr Alisher but to those affected.
Brisbane Lord Mayor Graham Quirk said the driver was a casual worker who had only been employed for a few months.
Mr Quirk said flags would be flown half-mast at council facilities on Saturday as a sign of respect.
Police Commissioner Ian Stewart says counter-terrorism authorities are involved in a homicide investigation but he there is nothing so far to suggest terrorism-related links.
Manmeet Alisher stood 'little chance' of survival
The attack left police, witnesses and workmates reeling.
Queensland Police Commissioner Ian Stewart said six passengers on the bus were taken to hospital suffering smoke inhalation and minor injuries.
He paid tribute to the heroic actions of a taxi driver who saw what was happening on the bus and kicked in the rear door of the burning bus, allowing them to escape.
"While we don't know the actual motives at this stage, I want to reassure the community that we take these incidents very seriously and that is why, as a precaution, officers from the State Security and Counter Terrorism Group have also been involved in this investigation," he told reporters.
Mr Stewart has said there was nothing to suggest the attack was racially motivated.
"We do not believe at this stage that there is any evidence linking this to a racial complaint or concern by either of the people involved."
The man's horrific death was likely captured on cameras installed on Brisbane City Council busses.
The crime played out in full view of horrified onlookers and just four weeks after the state government finally announced a review aimed at halting escalating attacks on bus drivers.
Mr Stewart appealed to anyone who might have footage of the attack to come forward. He said witnesses had been traumatised by what they saw.
Taxi driver Aguek Nyok, who kicked out the back door of the bus as it stood burning at the bus stop, is being hailed a hero for saving passengers, including children and their terrified mothers.
But there was nothing he could do to help the driver, who was hired by the council as a casual driver just a few months ago.
Veteran police Superintendent Jim Keogh says the attack appears random and without motive.
"The fire was substantial, he (the driver) would have stood little chance," he said.
"Words escape me. It's a horrific incident."
Premier Annastacia Palaszczuk said this week had been one of tragedy for Queensland, with the attack coming just a few days after four people died on a ride at Dreamworld on the Gold Coast.
She said the horrific nature of the driver's death was difficult to comprehend, and like the Dreamworld tragedy, there were witnesses who would need help to get over what they'd seen.
"I know that all the thoughts of Queenslanders are with this young man's family," she told reporters.
Flags at council buildings will be flown at half mast on Saturday as a mark of respect.
The taxi driver credited with saving terrified passengers has told of his confusion after coming across the blazing bus.
Mr Nyok began kicking frantically at a back door when he heard people screaming to get out.
"I thought the driver would open the door for them but nah, I stood a few seconds and nothing was happening so I decided to do something about it," he told the Nine Network.
"Everyone was shaking ... I was just holding the door until the last one got out."
Witness Clair Savage said the cabbie was a hero.
"I just said to him 'you just saved people's lives'," she said.
The passengers have been treated for smoke inhalation and shock and Supt Keogh said they were visibly traumatised.