Agostino Cuntrera, 66, is believed to have been killed in St-Leonard on Tuesday. (CBC)

A well-known member of the Montreal Mafia was one of two men killed in a shootout in the city's east end on Tuesday that authorities say was a settling of accounts.

Montreal police have confirmed Agostino Cuntrera, 66, was killed in broad daylight in front of a business he owned in the St-Leonard borough.

The other victim might have been his bodyguard or driver, according to media reports.

Cuntrera was closely connected to the Rizzuto crime family and well known to authorities. He is believed to have taken over Montreal's Mafia after its presumed boss Vito Rizzuto was jailed in the United States in 2007.

His death appears to have been a revenge killing of sorts, but authorities aren't revealing their theories.

"It might be a conflict between groups," was all Montreal Insp. Bernard Lamothe would say in an interview on Wednesday.

Gunshots heard

Montreal authorities say several gunshots were heard at the scene of the shooting, which took place in an industrial area of the borough. Eyewitnesses say they saw a black Chevrolet Impala leaving the area after shots were fired.

Cuntrera was shot in the head and declared dead on the scene. The second man, who is not identified, was hospitalized with life-threatening injuries and died shortly after.

Two people were arrested overnight but later released when police found they had no connection with the case.

The department's major-crimes investigators set up a perimeter Tuesday afternoon and combed the area for clues until early Wednesday morning.

Investigators are planning to meet with witnesses.

Mafia watchers say the Rizzuto clan has faced escalating challenges to its leadership since Vito Rizzuto's incarceration in a Colorado prison.

Tuesday's killing is the third violent incident to strike the close-knit family in the last year.

Last month, Paolo Renda was abducted from his car while running errands in Montreal's northwest end. Renda is believed to be the right-hand man to Nicolo (Nick) Rizzuto, presumed patriarch of the clan and Vito's father.

Vito Rizzuto's eldest son, Nick Jr., was gunned down in the middle of the afternoon last December.