A man was seriously injured when he tried to protect his father from an armed intruder during an alleged home invasion in Melbourne’s west.

Police say a man armed with a knife entered a home on Ridley St, Albion about 8.10pm on Sunday.

WATCH THE VIDEO ABOVE: Man defends elderly father from home invader

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The occupant of the home, an 84-year-old man, was alerted to the intruder’s presence after his dog started barking.

The offender allegedly demanded the elderly man hand over his car keys and when he refused, he punched the victim in the face.

Police say the victim’s 50-year-old son, who lives next door, heard the disturbance and ran to his father’s home.

He confronted the offender but was stabbed multiple times.

The man managed to overpower the intruder and held him down until police arrived.

The 50-year-old was taken to hospital in a serious condition, while the intruder, believed to be aged in his 40s, was also taken to hospital with serious injuries.

He remains under police guard.

The 84-year-old was taken to hospital with minor injuries.

CCTV shows police arriving at the home, with one officer heard yelling “drop it”.

One neighbour told 7NEWS the incident was “a bit distressing”.

“I just looked out the front door and there was a lot of commotion, obviously police and (the) ambulance,” he said.

Police are continuing to investigate what happened.

No charges have been laid.

Anyone with information is urged to contact Crime Stoppers.