Wigan North Western station has been shut since parts of a railway arch fell onto parked cars at about 8.40am today.
Virgin and Northern Rail services have been beset by delays throughout the morning.
Northern and Arriva North West rail companies said there could be severe delays for some time.
Greater Manchester Police said no injuries had been reported and the station would remain closed until further notice.
The A49 Queen Street, Wallgate, Great Georges Street, and King Street West have all been closed to traffic.
Virgin Trains posted on its website to say disruption is expected to ease this afternoon.
Passengers are urged to check with their provider for updates.
A police spokesman said: “Shortly before 8.40am on December 1 police were called to Wallgate, Wigan, to reports of a collapsed arch.
“Officers attended and found a wall has collapsed onto parked cars.
“Road closures are in place on Queen Street, King Street West, Wallgate and Great George Street. Wigan North Western has been evacuated and closed while the area is secured.”