Eight men and one woman are in custody after Montreal authorities arrested them Wednesday on suspicion of being members of rival street gangs operating on the West Island.

Montreal police say they were led to the suspects after residents in Pierrefonds and Dollard-des-Ormeaux contacted authorities last summer to report a marked rise of violent incidents in their neighbourhoods.

"They were fighting for the territory of drugs, so they were trying to influence or get rid of the other groups, so there were shootings, there was intimidation and assaults," said Commander Antonio Iannantuoni.

"They were trying to get at their rival gang. There were attempted murders, shootouts that occurred."

The suspects, aged 20 to 27, face several charges including murder, conspiracy to commit murder, and extortion.

Police are calling their arrests a sort of tying up of loose ends, months after a major sweep last August in which they arrested 39 people and seized machine guns, bullet-proof vests, drugs and $100,000 in cash.

The suspects arrested this week are due in court Thursday for their bail hearings.