POLICE have vowed to "dry up the supply" of guns and ammunition in the northwestern suburbs after the past week's triple shooting that left two men dead and another in hospital.

Raids yesterday morning by detectives working in Taskforce Acer 17 netted firearms police feared could be passed to criminals.

The weapons were held legally by registered gun owners, but police intelligence revealed 20 had "connections to family or associates who were persons of interest to the Acer Taskforce team".

Officers simultaneously hit 21 properties at 8am to ensure the licence holders were complying with all conditions.

A total of 21 guns - including 15 shotguns and ammunition for an AK47 rife - were seized.

The raids came after two men - one being convicted criminal Omar Taha - were shot dead at CBD Smash Repairs in Florence St, Brunswick, on Thursday afternoon.

A third man, Ali Kassab, 25, is believed to have been shot in the arm and leg and is receiving treatment at the Royal Melbourne Hospital while under arrest and with a police guard.

All three men were known to police and it is believed the shooting happened because of a $50,000 debt.

The homicide squad and Santiago taskforce are continuing to investigate.

The licence raids yesterday - carried out by Acer Taskforce, which supports Santiago - were in Greenvale, Meadow Heights, Campbellfield, Coburg, Fawkner, Hadfield, Reservoir, Preston, Brunswick West, Altona North, Altona Meadows, Hoppers Crossing and Keilor East.

Originally published as Shotguns seized in northwestern suburbs