Mahmoud Karam, who was shot dead in Campbellfield, had made several enemies throughout his underworld dealings

A 60-year-old man who was executed by gunmen on a nature strip had been involved in a years-long rivalry with major gangland figures.

Police at the scene in Campbellfield where Mahmoud Karam was shot. Picture: Andrew Henshaw

A man executed in a targeted hit in Melbourne’s north had been involved in a years-long rivalry with major underworld players.

The Herald Sun can reveal that gunmen opened fire on Mahmoud Karam, 60, on a nature strip in Campbellfield late on Friday night following a slew of tit-for-tat attacks believed to have been sparked by a large debt.

Paramedics rushed him to hospital but he died from his gunshot wounds.

It is understood Mr Karam, from Craigieburn, was aware he was under threat from fellow underworld heavy hitters in the lead-up to his death and had armed himself with a gun.

Mahmoud Karam was shot and killed in a targeted ambush.

Homicide detectives found what appeared to be a sawn-off shotgun, possibly belonging to Mr Karam, under a car outside the Gentles Ave home where the gunmen had ambushed him about 10.10pm.

Several underworld sources told the Herald Sun that Mr Karam had made several enemies throughout his underworld dealings, including at least two major figures living overseas.

One possible line of inquiry would be whether those behind Mr Karam’s execution had planned the hit overseas or before fleeing the country.

It is understood a significant sum had been placed on the 60-year-old’s head, and that the gunmen who carried out the shooting stood to share a profit from the paid hit.

Mr Karam’s assassination has ignited talks of potential reprisal attacks, as several sources with close knowledge of his dealings believe key players would refuse to let his death go unpunished.

Detectives will probe whether Mr Karam was lured to the residential Campbellfield street to be ambushed.

CCTV from a nearby home captured up to 15 gunshots being fired.

The footage also captured a speeding Porsche away before a burnt-out car was found dumped on Northbourne Rd about 11pm.

Exactly how many weapons were involved in the shooting or whether Mr Karam fired any gunshots will be examined by investigators.

A 20-year-old Yarraville man and a 22-year-old man from Westmeadows remained under police guard in hospital on Sunday.

They came to the attention of police after they were dropped off at a hospital following the attack.

It is not known if they suffered gunshot wounds or burns.

Victoria Police’s VIPER Taskforce, which monitors organised crime in Victoria, questioned nearby residents at the weekend.

Victoria Police Acting Superintendent Kelly Walker said on Saturday that detectives would remain open-minded about the motives behind Mr Karam’s killing.

“Homicide Squad will canvas all avenues available to them, extensive CCTV in the area, we’ve got the vehicles and obviously witnesses,” Ms Walker said.

“We want to provide the ­reassurance that we believe that (it was) targeted and provide the community the reassurance that we are exhausting all investigative ­avenues.”

Anyone with information should contact Crime Stoppers on 1800 333 000.

Originally published as Mahmoud Karam, who was shot dead in Campbellfield, had made several enemies throughout his underworld dealings