Twenty-six people were hurt on Friday, some critically, after a man set fire to a busy bank in Australia with one witness saying he heard a "big blast" and children screaming.
Police said the man entered the Commonwealth Bank branch in the Melbourne suburb of Springvale with flammable liquid. Some reports said he doused himself with the accelerant and went up in flames, although this was not confirmed.
"He had some sort of accelerant with him. A container, not sure what he had. And somehow that accelerant was lit inside the bank," Inspector Jacqui Poida said.
The motive was not clear and Poida said it was too early to tell if it was terror related.
Paramedics said six of those injured were in a critical condition. One is believed to be the suspect, who is under police guard in hospital.
Fire crews were quickly on the scene with Country Fire Authority official Paul Carrigg saying the doors to the bank were shut when they arrived.
"The fire was inside the building. So they entered with breathing apparatus and hoselines. They rescued 25 people, with a range of injuries from minor burns and serious injuries," he said.
"You can look inside the bank, it's very black. There would have been a lot of flames to start with and a lot of smoke."
He added that "we understand that there's been an explosion in the bank".
Witness Ashley Atkin-Fone, hailed a hero after running into the bank to help, said he heard "a big blast" and children screaming.
"This kid comes running out all burnt, screaming his head off ... blood everywhere ... I was shocked for a couple of the minutes," he told the Herald Sun newspaper.
Atkin-Fone grabbed a fire extinguisher from a nearby shop and ran into the bank to try and put out the flames, saying: "What do you do? Instincts just kicked in."
Another witness Ernie Gonzalez told The Age newspaper that bank tellers had to run through the flames to get out of the building.
"I could see flames in the entrance and I could see people running out covered in charcoal -- they were black," he said.
The Commonwealth Bank, Australia's biggest, said the branch would remain shut for the rest of the day, with its response team on site.
"We are working closely with local authorities and emergency services," it said in a statement.
Emergency service workers are seen at a branch of the Commonwealth Bank after a fire injured customers in Melbourne on Friday.