Thirty-six of some of Melbourne's most modern trams will be pulled off the rails and inspected after one lost a wheel when it derailed in the city's east.
The C-class tram derailed, striking a parked car and causing minor injuries to one person standing near it, on Whitehorse Road in Balwyn about 10.15am on Tuesday, a Yarra Trans spokesman has confirmed.
There were no passengers aboard.
Yarra Trams spokesman Simon Murphy said the remaining 35 C-class will be pulled from service progressively for inspection following the accident.
"If you had a flat tyre on a car, you would check the other three to make sure there were no issues," Mr Murphy told AAP.
"We started doing that earlier on today, and basically we'll rotate trams in and out."
He said there was no timetable to complete the checks, and he expected a "normal peak service" on Wednesday.
The damaged tram arrived at a Yarra Trams depot for repairs late Tuesday afternoon.
It took six-and-a-half hours to clear the scene in Balwyn.
Mr Murphy said Yarra Trams would investigate how the accident happened.
He said it's unclear whether the wheel came loose before or after the derailment.
Rail, Tram and Bus spokesman Phil Altieri says the union has concerns about the safety of the C-class fleet.
"For a wheel to come off and a tram to derail, hit three motor cars is my understanding, some injuries have occurred, (it's) a major safety concern," he told the Nine Network on Tuesday.
"This is a catastrophe that's just waiting to happen."
The C-class or Citadis trams were introduced to Melbourne's tram system in 2001.
The high-capacity articulated trams were built by French manufacturer Alstom and have a low-floor designed for easier access by passengers who use wheelchairs or have mobility issues.