The suspect in an explosion at a Commonwealth Bank branch at Springvale, in Melbourne's south-east, is a member of the Burmese community who arrived by boat in Australia in 2013 and was seeking a temporary protection visa.

Key points: Suspect is a member of Melbourne's Burmese community, arrived on a boat in 2013

Suspect is a member of Melbourne's Burmese community, arrived on a boat in 2013 He was on a bridging visa, seeking a temporary protection visa and had missed a welfare payment

He was on a bridging visa, seeking a temporary protection visa and had missed a welfare payment One person is in critical condition, another is critical but stable, four others are stable

One person is in critical condition, another is critical but stable, four others are stable Victoria Police, arson squad continue to investigate incident

Twenty-seven people, including several children, were injured after a man walked into the bank in Springvale Road on Friday and started a fire.

Pamela Curr, formerly with the Asylum Seeker Resource Centre, said contacts had told her the man went into detention after arriving by boat and was then released into the community on a bridging visa.

The man had been waiting for a letter from the Immigration Department offering him a temporary protection visa (TPV), as a member of a cohort of refugees who were fast-tracked following legislation passed in 2014, Ms Curr said.

The ABC has been told those in the fast-track system were expected to receive a letter by the end of the year.

The Immigration Department said anyone who had not received a letter should contact them to make sure their contact details are up to date.

A member of the Burmese Rohingya community in Melbourne, Habib Habib, said the man was close to his friends in the small local community, and he was told the man had been struggling mentally and financially.

Mr Habib said the man was single and lived with other single men in Springvale.

"It should not have happened. It is nothing to do with Commonwealth Bank and the people with those injuries," Mr Habib said.

"So I'm very sorry for that."

He said the man was mentally ill and weighed down by financial problems and concerns about his immigration status and his family back home.

Mr Habib said the man was from the southern part of Myanmar, was a Muslim and identified as Rohingya.

The man arrived when he was under-age and should be cared for, Mr Habib said.

"His service provider should've been aware about that and Immigration Department must know about that," he said.

"They have to look after the people. They have responsibilities So maybe they are not doing enough."

Anxiety caused by TPV process

Mr Habib said the man had not yet received his letter inviting him to apply for a TPV, and Sister Bridget Arthur from the Brigidine Asylum Seekers Project said that would be causing him great stress and anxiety.

"Now as it's getting closer and they haven't got a letter they're thinking that they've been passed over or are gong to be sent back," she said.

"Then they're scared about the process itself.

"I know many who are just collapsing under the weight of it."

Sister Bridget said it was a fast-track system in name only with most people waiting four years to get a final determination on their status.

"There are just hurdles set up I think, to actually stop them getting what I see as justice," she said.

Two people in critical condition

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CCTV footage showed a man walking down the street carrying a petrol container moments before a loud explosion and fire at the bank.

A 21-year-old Springvale man is under police guard in hospital.

Six victims were taken to the Alfred Hospital burns unit.

One patient remains in a critical condition, but it is not clear if this is the suspect.

A second person is critical but stable, and four other patients are listed as being in a stable condition.

Monash Medical Centre cared for 13 patients, including three children. All were in a satisfactory condition.

Dandenong Hospital treated 11 patients.

Dr Rachel Rosler, the director of emergency medicine at Dandenong Hospital said it was a traumatic event for all of the injured.

"They were quite distressed at the time," she said.

"We were initially dealing with their medical problems then a lot of the impact of other things came on.

"The nurses looked after them, then the social workers came to talk to them, our psychiatric team was involved with a number of them."

A fire-damaged ATM outside the Commonwealth Bank in Springvale. ( APP: Julian Smith )

The bank on the busy shopping strip 23 kilometres from the Melbourne CBD, is boarded up.

On Saturday, locals said they were shocked by what happened.

"I heard about the news and I was a bit worried [about] one of my two friends working there," one woman said.

"[I'm] very, very scared, because you can see that this can happen any time," another woman said.