Switzerland's entire rail network ground to a halt on Wednesday, stranding an estimated 100,000 people for three hours.
Some 9,000 trains travel on the Swiss rail network each day
The nationwide network stalled after a power failure in the St Gotthard region of the Swiss Alps.
A spokesman described the failure of the country's famed rail network as "absolutely extraordinary".
The Swiss rail network is known for its reliability and punctuality, correspondents say.
"We have a power failure, a problem with power regulation," spokesman Jean-Philippe Schmidt told AFP news agency.
He said the problem started at around 1600 GMT during the rush hour, as people were making their way home.
Power began to return at about 1915 GMT and some trains started operating again.
It was the most serious breakdown in Swiss railway history. The only similar incident happened in 1997, when trains in western Switzerland were halted for 40 minutes.
Rail is the most popular form of travel in Switzerland.
Each year, the average Swiss clocks up some 2,077km (1,290 miles) on the tracks.
Switzerland's railway stretches 3,000km across the country and represents a vital freight passage through the Alps.