Sources told NY1 on Wednesday that two Metropolitan Transportation Authority employees have been suspended without pay in the wake of Tuesday's A train derailment inside a Harlem subway station.

A preliminary investigation shows the derailment was caused by a piece of replacement rail being stored on the tracks that wasn't properly secured.

Now, the MTA says two track maintenance supervisors in charge of the rail repairs face disciplinary action.

The agency says storing equipment in between tracks is a common practice, but adds the gear should be properly bolted down.

Spare rails are often stored by tracks to speed repairs. But MTA rules require securing each spare with four spikes and four anchors to prevent them from moving as trains pass.

Transit officials vowed to inspect every inch of track of spare rails that might not have been secured.

"The cause appears to be human error," MTA heads Joe Lhota and Ronnie Hakim said in a statement. "Not a track defect."

The southbound A train was nearing the 125th Street station shortly before 10 a.m. when its emergency brake was tripped.

34 people suffered minor injuries.Crews were working well into the Wednesday morning rush trying to fix damage at the station.

Straphangers who spoke with NY1 say despite residual delays, their commute went a lot smoother.

"I thought it was just going to be a disaster just coming out, more delays, more than even normal. But I was reallly surprised. Turned it over overnight , and got to where I need to be pretty early," said one rider.

"Yesterday, I got stuck on the C train for about a good half-an-hour, so today was a lot better," noted another rider.

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