Gunman's bizarre act before holding a father and toddler son hostage in tense Weir Views rooftop stand-off

A man armed with a high-powered rifle and on the run bounced on a trampoline before taking a father and his toddler son hostage in a tense stand-off with police.

The 26-year-old man, from Snake Valley in Victoria's west near Ballarat, remains in hospital after Victoria Police's Special Operations Group used an attack dog to take him down.

The elite camouflage-clad officers were seen on the roof of neighbouring homes in Weir Views, west of Melbourne , where the gunman had taken the dad and his one-year-old hostage.

Superintendent Michael Cruse said the man allegedly fired multiple shots at police after he carjacked a 70-year old woman around 2.30pm on Tuesday in Snake Valley.

The man used that car to make his way into the Melton area where cops deployed a police helicopter to track him for more than 100km to the Weir Views home where a dramatic siege took place.

Neighbours on Leon Drive told media the armed man was spotted playing on a trampoline in a nearby backyard before he forced his way into the home.

Supt Cruse confirmed the man had been observed behaving in a bizarre fashion immediately before taking the hostages, but wouldn't go into specific details.

'There was a period of time where he was behaving erratically in the backyard of the premises, yes,' he admitted.

Police further allege the man fired upon officers who first approached him in the area.

'We'll allege a shot is fired toward police. Police were able to retreat and again, very thankfully, they weren't injured,' Mr Cruse said.

Once bunkered inside, the man allegedly refused to allow his hostages to leave for two-and-a-half hours.

The surrounding area was placed into lockdown, with residents told to remain indoors as SOG officers surrounded the property.

Mr Cruse said police negotiators worked for hours to encourage the man to leave peacefully, but it was advice he refused to accept.

Shortly after 6pm, police believed they had made a breakthrough, with the gunman suggesting he would allow his hostages to leave unharmed.

But when the time came, police allege to man opened fire in a yet to be determined direction.

'At that point a tactical entry of the house has taken place by police. We'll allege at that point that a further shot was fired towards the police entry team and they were able to deploy a police dog and the male offender was taken down,' Mr Cruse said.

In a stroke of luck for the offender, Mr Cruse revealed one of the elite officers fired back, but did not hit the man.

Instead, the man suffered little more than a dog bite and remains in the Royal Melbourne Hospital.

He is expected to be released on Wednesday afternoon where he will face multiple charges including conduct endangering life.

The father and his child were physically uninjured in the incident, but are feared traumatised by the experience, as was the elderly carjack victim.

Supt Cruse paid tribute to the bravery of the SOG members in ending the siege without the loss of lives.

'All of the police that were present yesterday have got significant expertise in a variety of different areas,' he said.

'The Special Operations Group train for these incidences and I was (reassured) by having their attendance there.'

Supt Cruse said it was 'extremely lucky' that no police officers were killed in the incident.

'The offending is very serious and completely unacceptable that police members were exposed to this kind of danger,' he said.

'Having said that, we had a really strong plan and we tried to make it as planned and as safe as possible. But it is lucky.'

Police are now working to ascertain just how many shots were fired by the man and how many were aimed at them.

'We're unsure of the exact number of shots that were fired ... at the moment we're just working through it,' added Supt Cruse.

'There's some unaccounted discharges we believe and we're just trying to establish where they were directed and what the rationale for that was.'

None of the shots hit any police officers, but Supt Cruse said all police involved in the drama were receiving counselling over the coming days.