Masked intruders armed with a gun and a baseball bat have shot one man and bashed three other people in a Melbourne home.

Police found a 31-year-old man in his Tarneit home with a gunshot wound to his upper body just after 4am on Tuesday.

Three other people in the home - a 34-year-old man and two women aged 23 and 32 - were beaten with blunt objects, police say.

All four are in a stable condition in hospital.

Police say it appears the group was woken during the night by a group of about two to four people who had broken into the home and were wearing disguises or masks.

At least one offender was armed with a gun while at least one other had a baseball bat.

A large window at the front of the Conway Street house appears to have been smashed from the inside out.

Detective Sergeant Andrew Eyries says it's too early to say whether the victims knew the offenders.

"But what I can say is, of experience, these (incidents) are generally not of a random nature," he told reporters at the scene.

He would not say if the victims were known to police, but did say they'd been cooperating with police.

Neighbours later in the morning were surprised to learn of the shooting and police activity, having heard no commotion overnight.

"That's not unusual that neighbours don't hear a gunshot," Det Sgt Eyries said.

Police have begun gathering CCTV footage from homes in the area.