Transport Minister John Graham said all passengers had been taken off the train that was “entangled” in the wiring, as well as three other nearby trains that had come to a halt, by 6pm.

“This is a very serious incident in a critical part of the rail network and we apologise to all train passengers affected and trying to get home tonight,” he said.

“The position of the train at Strathfield [which] is a major artery of the network and has caused huge disruption.”

Graham said crews were working to cut the train from the wires and were assessing the recovery work required. He said authorities would provide updates on how that work was progressing, and the extent of any roll-on effects on the rail network for the morning peak.

Earlier, Transport for NSW Coordinator-General Howard Collins said all passengers inside the carriages had been reported as unharmed, but they could not be evacuated until it was safe to do so.

“The most important thing here is safety, making sure we do that under safe conditions and there’s no risk of the power being switched on by accident or other means,” Collins said.

Collins had emphasised the live wire was a “life-threatening” situation.

“If you get very near or touch wires with that amount of voltage and amperage, it will kill you straight away.”

The peak hour incident follows revelations this week that one in five Sydney peak-hour trains has run late over the past two months, despite a decade-long project to improve the network’s reliability – and the cost of upgrading critical infrastructure has now blown out by $266 million.

Trains were first reported as having come to a halt at platforms on the affected lines shortly before 4pm. Frustrated commuters gathered at train stations faced delays of 45 minutes and longer.

Twenty replacement shuttle buses were ordered to transport commuters between Lidcombe and Ashfield. An Uber price surge cap agreement was also activated.

At Parramatta station, large crowds grouped out the front of the Opal gates as staff temporarily blocked access to the platforms to avoid crowding. Just after 4pm, passengers were told by station staff there was “nothing happening between now and the next half hour or so” before replacement buses arrived. By 4.15pm, commuters were once again piling on to the platforms.

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Collins said authorities hoped the live wire would be isolated and fixed on Tuesday night, but warned the delays could continue in the morning.

He insisted the live wire problem had nothing to do with an ongoing dispute with rail unions, or maintenance standards.

“The overhead wire is maintained to a very strict standard... but like anything mechanical, there may be a reason why this has occurred,” Collins said.

“It is very unusual, but it does happen on overhead wire lines around every state and around the globe.”