Hundreds of people of all ages have gathered outside the Codiac Regional RCMP headquarters on Main Street, CBC's Neville Crabbe reported from the scene.
They lined up to shake hands and hug the RCMP officers who attended the event, he said.
Another vigil is underway at the nearby Riverview detachment, on Pine Glen Road.
Ellen Graham, a paramedic, helped organize the events.
She said she doesn't know any of the victims and was not involved in the response, but the shootings hit close to home and she felt compelled to do something.
The vigils are "to show support and to say thank you to our fallen and wounded members of the RCMP and their loved ones for all their hard work, dedication and sacrifice."
People were being urged to bring a candle, flashlight or glow sticks — anything that shines light into the night.
The front steps of the Codiac headquarters had all but disappeared by the time the vigil started, covered with hundreds of bouquets of flowers, signs bearing slogans of support and other items left as a memorial to the slain officers.
"It's really horrific that three of them were actually taken from us when all they were trying to do was protect us," said Melissa Brown.
Justin Bourque, 24, of Moncton, was charged Friday afternoon with three counts of first-degree murder and two counts of attempted murder in the shootings.
Bourque, who was arrested following a two-day manhunt, will remain in custody and is scheduled to return to court on July 3.
The officers killed were:- Const. Dave Ross, 32.
- Const. Fabrice Georges Gevaudan, 45.
- Const. Douglas James Larche, 40.
The officers injured were:- Const. Darlene Goguen.
- Const. Eric Dubois.
The CN Tower in Toronto will be honouring the three fallen officers by lighting the tower in red, blue and gold tonight.
Victoriaville Mayor Alain Rayes has also asked all Canadians to leave their lights on to honour the slain Mounties.
Books of condolences have also been set up in several locations, including the New Brunswick RCMP headquarters in Fredericton, the New Brunswick legislature in Fredericton, Moncton City Hall, Dieppe City Hall, Riverview Town Hall, and the Saint John Police Force headquarters.
Messages can also be sent to Condolences_Condoleances@rcmp-grc.gc.ca.
Meanwhile, the Rotary Club of Moncton, in partnership with the Mobile Giving Foundation Canada, and the RCMP Foundation, has set up a memorial fund to support the families of the slain officers.
Cellphone customers from across Canada can make a $20 donation by texting the keyword Moncton to the shortcode 45678.
“These families will need all of our support not just today, but for the years ahead," Rotary Club president Steve Beyea said in a statement.
The donation will appear on the customer's monthly bill and 100 per cent of the donation will go directly to the families in care of the RCMP Foundation.
“Mobile giving is a way in which Canadians from coast to coast can immediately express their support for these families," said Bernard Lord, president of the Canadian Wireless Telecommunications Association and former New Brunswick premier.