Commuter chaos which plagued the Armadale line on Wednesday was caused by a train striking a trolley, which authorities believe was put there deliberately.

According to a Public Transport Authority spokesperson, the train hit the trolley just before 5.30am on Wednesday, causing the trolley to become stuck under the train.

Crews worked to remove the trolley for around two hours before it was finally dislodged at around 7.30am.

The incident led to the closure of a section of the Armadale line between Cannington and Gosnells, forcing passengers to resort to emergency bus replacements.

The train was then sent to a depot for inspection.

While train services began running again at around 8am, normal timetabling did not return until after 9am.

While investigations remain ongoing, authorities believe the trolley was put there on purpose.

“It appears the trolley was deliberately placed on the rail line and investigations remain ongoing,” the spokesperson said.

If the perpetrator is caught, they could be facing a serious punishment.

“Anyone caught committing a crime on PTA property will be charged where evidence identifies those responsible,” the PTA spokesperson said.

“The offence of intent to obstruct or injure a railway under section 451 of the Criminal Code carries a maximum penalty of 20 years’ imprisonment.”