Six injured in explosion at Melbourne flat

Three police officers have been seriously hurt in an explosion at a Melbourne flat that injured six people.

Police were called to the Middle Park flat at about 9.15pm (AEDT) on Saturday after reports of a man threatening to harm himself.

As firefighters and police entered the second-floor flat there was a large explosion.

Three police officers were seriously injured and were taken to The Alfred Hospital.

Two female officers, including one suffering burns to 90 per cent of her body, remain in a critical but stable condition.

A male officer is in a serious but stable condition.

Two firefighters were also hospitalised with non-life-threatening injuries, along with the male occupant, who remains under police guard.

Acting Assistant Commissioner Doug Fryer said police were still piecing together what happened.

"There could have been injuries to other people; thankfully there was not - only those inside the room," he told reporters.

"This is part of the danger of law enforcement. Most days everyone gets home, but unfortunately we've had a tragedy."

Police have asked for anyone with information about the incident to come forward.

* Readers seeking support and information about suicide prevention can contact Lifeline on 13 11 14 or Suicide Call Back Service 100 659 467.