Yobs hurled a brick at a tram window during the Friday rush hour.
The tram was travelling on the Rochdale line and was attacked near the Barlow Moor Road stop in Chorlton .
It happened at around 5.30pm on Friday.
Eyewitnesses said that 'kids' were throwing bricks at the windows.
One window was completely shattered.
The tram had to be taken out of service and back to the depot to be repaired.
Metrolink confirmed that nobody was injured.
Transport bosses said they'll be reviewing CCTV footage of the incident to try and find those responsible.
Witnesses tweeted about the incident.
One angry commuter, Mand Cashin, said: "Friday night commute ruined by a kid throwing a brick through the tram window at Barlow Moor Road."
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Transport for Greater Manchester said that 'vandalism will not be tolerated'.
A TfGM spokesperson said: "At around 5.30pm yesterday evening, a driver noticed that a window had been smashed at Barlow Moor Road.
"Fortunately, there were no passengers injured and the tram was promptly taken out of service and returned to the depot.
"Irresponsible acts of vandalism will not be tolerated and we will be reviewing CCTV footage alongside the TravelSafe team and our partners at GMP to identify those responsible."
