All 12 of the new AZUR metro trains are going to be pulled temporarily from the Montreal metro system following a breakdown over the weekend.

STM President Philippe Schnobb and Montreal Mayor Denis Coderre made the announcement Monday morning at a lengthy technical briefing.

“It is an issue but people, our taxpayers, they deserve answers,” said Coderre.

On Saturday, a malfunction in one of the new trains shut down a portion of the Orange line for several hours.

Coderre said despite the trouble the issue was well handled with 31 STM employees scrambling to check each train on the Orange line -- and the tracks from end to end.

The STM's general manager confirmed that a problem occurred with a tire in one of the new AZUR cars which ended up damaging the track.

He elaborated at Monday’s briefing, explaining that they believe the AZUR’s electrical contact pad damaged some signaling equipment as it was passing through the Du College station.

"What we know is that there is a bizarre interaction between the two of them, but we don't know which is the problem," said Luc Tremblay, the General Manager of the STM.

He said the transit agency is not yet clear on why the issue is occurring with the AZUR and newer MR-73 cars, but that it is not an issue with the older MR-63 cars.

Chair Philippe Schnobb said problems should be expected during the break-in period.

"This happens everywhere in the world and in some cities it's worse than it was here," he said.

Just last week the STM promised improved metro service and began running an extra-service schedule for its Orange and Green lines.

On Sunday, Projet Montreal leader Valerie Plante said the breakdown is proof the city has not invested enough into public transit.

“When there’s a breakdown like [Saturday], it’s normal that it’s not functioning well,” she said. “To me, it’s not so much about the AZUR trains at this point; it’s more about how the entire system is not sufficient.”

"It's a big source of frustration when you're waiting there with your kids and your packages and you're stuck there."

The new AZUR metro cars are manufactured by Bombardier and Alstom and were first rolled out last spring. A total of 52 trains will gradually be introduced into the system by the end of 2018 at a cost of $1.2 billion.

“The system is so fragile already. The city hasn't invested into buses in the last years so right now there are 200 buses missing already,” said Plante. “We need more buses but we also need to put together a plan for in situations like this.”

The STM has added new buses to its service this year, especially in the southwest borough.

A spokesperson for the STM said it does have a plan for breakdowns and on Saturday night added 25 buses to help with transport.

It also said that making announcements in the Bell Centre at the Montreal Canadiens game helped mitigate the issue by giving fair warning to public transit users.