Police say a gas explosion at a Melbourne flat which seriously injured two police officers making a house call was most likely part of a suicide attempt and not malicious.

Two female police officers are fighting for their lives after the explosion occurred on Hambleton Street in Middle Park on Saturday night.

A male officer and two firefighters also were injured.

An LPG canister exploded as emergency services were checking on a man believed to be in his 40s after he had threatened to self-harm.

Victorian Deputy Police Commissioner Tim Cartwright says while police are still trying to establish the facts, “indications are it was not a malicious act”.

He says the tenant, who needed treatment for burns, is under police guard in hospital.

“That is out of an abundance of caution,” Deputy Commissioner Cartwright said.

“Until we know what has happened, we will continue to have a police guard on the man.”

“He’s not in a fit state to talk.”

6 seriously injured in gas explosion at a flat in #MiddlePark, incl. 3 police officers. @LexiDaish reports #9NewsAt6 pic.twitter.com/8DCkjSGrev

— Nine News Melbourne (@9newsmelb) January 5, 2014

Deputy Commissioner Cartwright says the two injured female police officers are in a critical condition and fighting for their lives after suffering serious burns.

They have both undergone surgery.

Anyone needing help with a personal crisis can contact Lifeline on 13 11 14.