Update, 6pm: Train services on the Joondalup line are not expected to return to normal until Friday after a power line crashed onto a city bound train this morning.
Passengers endured a terrifying few minutes when a downed power line hit the train, slamming against a window and sending people ducking for cover as they feared the windows could smash.
The power line and supporting poles were ripped out as the Joondalup line train continued along the track for about a kilometre after becoming tangled in the line.
Debris showered vehicles travelling along the freeway. Passengers were initially stranded on the disabled train this morning.
Train transport was in chaos with hundreds of people stranded at stations. The interruptions have extended into this afternoon with replacement buses used to clear the backlog.
Trains are running between Clarkson and Whitfords, and between Stirling and Perth but replacement buses are operating between Stirling and Whitfords.
Trains on the Thornlie Line between Cannington and Thornlie were also replaced by buses during peak hour after they were cancelled due to a technical issue. Trains on the line returned to normal on 5.30pm.
The issue was not linked to the Joondalup interruptions.
Transport Minister Troy Buswell said the trains may not return to normal until Friday.
Mr Buswell described the incident as significant and said it had caused damage to 1.5km of overhead wire and to some rail infrastructure.
He said all rail crews were working to repair the line and a full investigation was underway to find the cause.
Extra buses would be used tomorrow to take patrons into the city.
In a statement this afternoon, Transperth also said full train services were not expected to return to normal before Friday morning.
The State opposition has called for a full inquiry into the interruptions, with the findings made public.
Opposition transport spokesman Ken Travers said the public needed to be reassured it was not the result of cuts to the Public Transport Authority's budget.
“I’ve been regularly receiving feedback that areas like maintenance have certainly been part of where the PTA is looking for savings,” he said.
“Just as an example, about 12 months ago they tried to change the inspection regime for the transformers.
“We’ve had now over the last few years more significant shutdowns of the rail system for as long as I can remember.”
Mr Travers said crews appeared to be addressing the problem on the Joondalup line, but, if possible, they needed to work around the clock to restore service as soon as possible.
Power has now been restored to most of the line but the damaged cable is still being repaired.
Earlier today, Sergeant Steve Luplau said the train lines would be closed all day, with the "best-case scenario" being one line opened at around rush hour.
If the line was opened, there would be a substantially reduced service with single trains going between Whitfords and Leederville.
Sgt Luplau said commuters could expect significant delays and advised people who intended to use the Joondalup train line to make alternative travel plans.
Traffic on the Mitchell Freeway was also delayed after the right lane was closed northbound between Karrinyup Road and Erindale Road in Balcatta while repair works were carried out on power lines.
The lane has since been re-opened but heavy delays remain and traffic is heavy from the Narrows Bridge to Reid Highway.
University student Holly Gretton, 18, was on the train when the power lines came down.
"The first we heard of it was a knocking on the roof of the train," she said. "Then there was lots of loud bangs; the wire was hitting the train.
"One of the windows was cracked and we could see the wire hanging down over the train."
She said passengers sat on the floor of the train as the driver addressed them over the PA system.
"For a while we were sitting there in the unknown. When the driver told us it was a life-threatening situation, that's when everyone realised the magnitude of it," Ms Gretton said.
"We couldn't use the emergency exits because the power wasn't on, and obviously it was too dangerous to use them because we weren't sure of what the damage was."
Ms Gretton said the crowd had remained calm throughout the 40-minute wait on the train.
City worker Fiona Metcalfe initially feared the worst. "I thought maybe someone had jumped in front of the train, but I realised we hadn't gone under a bridge," she said.
She said the initial reaction of passengers had been panicky.
"People were panicking and trying not to touch the metal, they were getting away from the windows because they thought they would smash," Ms Metcalfe said.
"But everyone calmed down - in the end we were just sitting there getting hot until they opened up some doors."
Police boarded the stranded train just after 9am to check on the passengers.
"They came to make sure everyone was OK and that no-one was trying to jump off, they were worried the line or the train would be electrified," Ms Metcalfe said.
Public Transport Authority spokesman David Hynes told 6PR the safety of the passengers had been the highest priority.
"We kept people on the train until we were absolutely sure there was a safe exit for them," Mr Hynes said.
Traffic heading into the city from the north was clogged as motorists survey the train damage.
A motorist told ABC radio that he noticed something was wrong on the line around the Erindale Road overpass just before 8am, with wires above the train appearing tangled.
Paul said debris was flying "everywhere" as a result of the train ripping the line as it continued to travel along for about 500m to 1km.
He said it would have spooked motorists driving in the right-hand lane near the train line.
Paul said the train was tearing down the line along with parts of the poles.
It was "quite a mess, with bits of wire hanging down and bits of debris", possibly hitting cars, he said.
The train was "certainly ripping the line down" as it continued towards Stirling Station.
The four-car train appears to have a broken window.
A passenger told 6PR that the live wire was whipping at the train's windows.
The window above the woman's head cracked and passengers dropped to the floor, she said.
A female passenger described how they heard a "loud crashing noise" before the overhead cables came down and started hitting the glass windows, leaving cracks.
Mr Hynes said the broken cables posed no risk to passengers' safety and there was "no possibility of anyone being electrocuted".
The incident would be investigated thoroughly to identify the fault. He doubted it was caused by strong winds overnight.
The incident had caused a fair amount of damage to overhead wires and it was difficult to speculate when the line would be operating again.
The incident has affected trains between Clarkson and Whitfords and Perth and Leederville.
Replacement buses are operating at stations.
Mr Hynes said people had been kept on the damaged train initially because of concerns about the live power line, but later because there needed to be a system in place to help people off the train and to a safe area.
He said there was no risk that the cables could break through the train's windows and electrocute passengers.
The windows were made of "really tough glass" and it would be extremely difficult for the glass to shatter, even if they did break, he said.
Commuters are being asked to find alternative transport.
The right-hand lane of the freeway, heading north, has been blocked to motorists to enable buses to travel through traffic.
The train remains stranded between Warwick and Stirling stations.
Police officers believe the train line will remain closed all day from Whitfords to Leederville.
Hundreds of people are outside Leederville Station and a crowd of more than 500 stranded passengers is at Stirling Station.
Replacement buses are arriving every five to 10 minutes.
Commuter Robert Tomlin made it on to one of the replacement buses just before 8.30am.
"There was a huge amount of people at Stirling when I got there," he said.
"As I was walking into the station people were heading back to their cars."
A woman at Stirling station said the crowds waiting at the station were building up and it was getting worse.
She said passengers had been told that 35 buses were being sent from Perth to the northern stations to collect people and take them to the city.
"We were told they were picking people going north first, but it seems to make more sense to get people going into the city first," said the woman, who declined to be named.
Perth Transport Authority spokesman David Hynes said the broken cables posed no risk to passengers' safety and that there was "no possibility of anyone being electrocuted".