The State Government says a full investigation will be conducted into what caused a major disruption to train services in Perth.

A Perth-bound train was forced to a halt near the Stirling Station just before 8:00 am when overhead power cables crashed onto its roof.

Passengers say they ducked as cables struck the carriage windows, causing them to crack.

The Transport Minister Troy Buswell says the Public Transport Authority will conduct a full investigation into the incident.

"That investigation will then be provided to the Government's independent rail safety supervisor, the Office of Rail Safety," he said.

A commuter inside the stranded train on the Joondalup line near Stirling station. ( Piper Swift )

A commuter on board, Piper Swift, says the train was pulling up to the station when they heard a loud bang.

"[We] heard a loud crashing noise as though something had hit the train. [I] thought it sounded like something had hit the train and then the overhead cables came down," she said.

"The overhead cables just started hitting the windows and I think that might have hit the power lines.

"They started hitting the glass inside so everyone started ducking. Luckily it didn't smash through but there are cracks in the glass, and so then obviously the train stopped."

A witness who was driving on the freeway, Paul, says power lines appear to have been destroyed.

"You could see the riser or whatever it is on top of the train that touches the power lines was tangled up in the lines and it was basically tearing the line down as the train went down the freeway," he said.

He says the train kept travelling for about a kilometre.

"It was going along at full speed, it was just tearing the line down and part of the poles that hold the line up and the top of the train," he said.

"It was certainly quite a mess with bits of wire hanging down and debris flying all over the place."

Not at risk

Ms Swift says the mood on the train was not too bad.

"I think the police boarding the train definitely eased everyone's worries," she said.

"Everyone was worried; they were saying it could be life threatening because the train could be electrified, everyone was pretty worried."

The passengers were escorted off the train.

The Public Transport Authority's David Hynes says despite the broken cables there was no risk to passengers.

"There's some reports have come through that a wire came down and touched the rail cars," he said.

"That may well be the case, I would want to assure people that there's no possibility of anyone being electrocuted.

"It just doesn't happen, it's not the way it works."

The PTA says the northern line problem is unlikely to be resolved before Friday.

Trains are still running between Clarkson and Whitfords with replacement buses operating between Whitfords and Leederville.

Mandurah line trains are running through Perth up to Leederville and the PTA says other lines, including Royal Show services, are not affected.



