TERRIFIED passengers threatened to break a window on their St Kilda Rd tram when the driver refused to open the doors after it was rocked by an explosion caused by overhead wires.

Passenger Kate Grandison told the Herald Sun she and a work colleague were on the tram — carrying about 30 passengers — when the wires failed, causing the side of their carriage to catch fire about 9.30am at the corner of Toorak Rd.

“We heard an explosion and saw sparks flying and smoke,” she said.

“Our immediate reaction was to move away from the burning window and run.

“Passengers kept calling out to the driver to release the doors but nothing happened.

“After the second explosion myself and other passengers moved to the front of the tram and threatened to break a window if the door was not released.

“The tram driver appeared to have gone into total shock.

“We were just trapped in there, I thought the whole tram was going to explode. I’ve never experienced something like that before, my heart was going at a million miles an hour.”

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media_camera The power lines struck the side of the tram. Picture David Crosling

media_camera A black scorch mark can be seen on the side of the tram. Picture: David Crosling

All outbound trams running at the time of the incident were turned back towards the city.

Replacement buses ferried people from outside the Melbourne Arts Centre along St Kilda Rd.

Yarra Trams said services had resumed as of midday.

“Services were disrupted at around 9.30am when an overhead power line came down near the corner of St Kilda Road and Toorak Road,” Yarra Trams spokesman Simon Murphy said.

“We are investigating a potential fault with the tram, which could have caused the damage to the overhead wire.

“We understand the effect that incidents like this can have on our passengers, and we appreciate their patience while our crews worked to safely restore services.”

Buses are still being used to ferry passengers along St Kilda Rd as the timetable returns to normal.

Diane Oliver, who works on St Kilda Rd, described the city’s public transport system as a “nightmare”.

“There’s always something going wrong,” she said.

“We were told to get on a tram and then jump off at the Arts Centre and wait for a bus. There’s never any details, how long do I have to wait?

“You don’t even know if you can get to where you want to go, it’s just typical of the transport system.

“It’s a terrible day and now I’m going to have to walk.”

media_camera Emergency crews repairing the overhead lines. Picture: David Crosling

media_camera The incident caused long delays for St Kilda Rd commuters. Picture: David Crosling

Witness Kate McIntyre said she was sitting in her car at the traffic lights when she heard a massive explosion.

“It sounded like a sheet of concrete dropping,” she said.

“I looked over and could see flames under the tram and then it exploded again and there was fire up the side.

“All I could see was flames and the people in there and I thought ‘ my god, it’s going to go up’.

“It was a full tram, there were mothers with prams and babies trying to get out.”

Local workman ran over and helped usher people to safety, Ms McIntyre said.

A front window on the tram was visibly scorched in the blaze.

Update St Kilda Rd & Route 58: trams have resumed following the earlier disruption. Delays will occur as we work to restore frequency. (1/3) — Yarra Trams (@yarratrams) September 5, 2017

Cafe Rosco owner George Gereige said he saw the whole ordeal unfold through his front window.

“I heard a couple of bangs and then I looked out and saw the cable jumping from the tram,” he said.

“Luckily, no one was standing near the burnt window or under the power line, it could have been catastrophic.

“The workers blocked the area off so no one could get near it before the fire crews came.

“This cable was just put in a few weeks ago, so it’s either not up to standard or faulty.”

@yarratrams hi so am i supposed to wait for st kilda road tram or what? I paid monthly for this and i need to take alternative transport??? — Patrick Rompis (@DarkDells) September 5, 2017

One witness told 3AW the tram exploded twice within a matter of seconds: “People were trying to get off and then it exploded again.”

A Metropolitan Fire Brigade spokeswoman said when fire crews arrived at the scene about 30 people had been evacuated from the tram.

“The tram had overhead lines that came off and caught the tram alight,” she said.

“The fire is out. The situation is under control.

“We believe there are no injuries.”

Tram routes 1, 3, 5, 6, 16, 64, 67 and 72 were affected in both directions, with trams halted between the Arts Centre and St Kilda Junction.