Six people have suffered serious burns and more than 20 have been treated for breathing difficulties after a young man allegedly set fire to a suburban Melbourne bank branch.
The Commonwealth Bank in Springvale has been evacuated and the 21-year-old suspect has been placed under police guard in hospital where he is in a serious condition.
Three children are among the injured, receiving treatment for breathing problems.
Emergency crews were called to the branch just before midday on Friday.
A brief video filmed by Twitter user @sunprawn shows low orange flames on the floor of the bank and a plume of smoke beginning to emerge from its open glass doors.
As of 1.30pm, ambulance officers had treated 27 people, six of them suffering serious burns who were rushed to The Alfred hospital.
The other 21 - including three children - are in a stable condition after receiving treatment for breathing problems. Ten of that group were sent on to Monash Medical Centre and 11 to Dandenong Hospital.
"Police responded to reports that a man had allegedly set fire to a Springvale Road bank in Springvale about 11.30am today," a police spokeswoman said in a statement.
"The man has been taken to hospital in a serious condition under police guard."
Police have closed Springvale Road between Balmoral Avenue and Windsor Avenue.
Four CFA trucks were deployed with the blaze brought under control by 12.25pm.
The Commonwealth Bank in a statement said its first priority was the safety of staff and customers.
"As a result the branch will remain closed for the rest of the day," a spokesman said.
"Our response team is on site and we are working closely with local authorities and emergency services."
A worker from a neighbouring clothing store told AAP he heard an explosion and called emergency services.
"I heard an explosion but not that loud, though," the man, who didn't want to be named, told AAP by phone.
"I just walked out of the shop to have a look and I called triple-zero.
"There was lots of smoke coming out of the bank."
Five or 10 minutes later, injured people came from the Commonwealth Bank with burns, he said.
Police subsequently told the retailer to close his store and stay inside.
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