Hundreds of passengers faced rail chaos as signal problems brought rush-hour trains grinding to a halt.
Several trains were cancelled and many others were delayed from 4pm yesterday, due to a power cut on the Leicester to Loughborough line at Sileby.
There are usually eight trains an hour running on that stretch of line but all services were halted for an hour-and-a-half, leading to what rail bosses said was "serious disruption" as repair crews worked on the problem.
The route connects the north and London. Passengers travelling to and from St Pancras, Market Harborough, Nottingham, Derby, Loughborough, Lincoln, Sheffield and Leeds were affected.
Replacement coaches were put on for some trains and, at one point, queues of people formed on the street outside Leicester station, while others made alternative travel arrangements.
As Network Rail crews tried to fix the problem, a temporary signal system was introduced so some trains could begin moving again, but bosses admitted it was a "much-reduced" service.
Power was gradually restored shortly before 6pm, but Network Rail said the disruption would carry on for hours afterwards.
At 6.30pm, dozens of people were still packed into the main hall at the station waiting for their delayed trains.
Among them was Craig Simpson, 29, from Leicester, who planned to catch the Nottingham train shortly after 5pm to see relatives, but he was still waiting at 6pm.
He said: "It's a bit of a shambles, really. I'd have been better off driving."
Alison Stafford, 20, from Glenfield, who was hoping to catch the delayed 4.44pm train to Leeds, said: "It's really annoying.
"People have been fairly calm about it but it's really frustrating for passengers when we're told it's a power cut but it causes so much disruption."
At 6.10pm, Chris Hepworth, 34, from Kirby Muxloe, was still waiting for a friend on the St Pancras to Leicester train, which was due to arrive at about 5.30pm.
He said: "She rang me at 5.20pm to say the train still wasn't moving and they were in the countryside somewhere.
"There's still no idea of how long it'll be."
A spokeswoman for East Midlands Trains said: "There was a power failure between Loughborough and Leicester which affected signals.
"It started at about 4pm but by 5.30pm power on one of the lines had been restored and we had two trains an hour going in each direction. It would be four in each direction normally."
A Network Rail spokesman said: "Although power was restored at 5.50pm, it would take most of the rest of the evening for train services to fully recover.
"When something like this happens, you get trains in wrong place and train crews in wrong place and it takes time to recover."
The incident was not linked to last Friday's crash near Barrow-upon-Soar, when a passenger train hit a footbridge which had collapsed on to the tracks.