Two track maintenance supervisors have been suspended following Tuesday morning's A train derailment that left 34 injured and forced frightened passengers to evacuate through the subway tunnel.

The two supervisors will be suspended without pay pending the outcome of a formal review process and the final outcome of the derailment investigation, MTA spokesperson Beth de Falco told Gothamist. Jim Ganon, the Director of Communications with the Transit Workers Union, told us "two Track Maintenance Supervisors [are] taking the hit."

The suspension was ordered by their boss, and the two workers were made aware of the order at 1:30 a.m. on Wednesday morning, according to sources who spoke with the Daily News.

Hours earlier, the MTA blamed the derailment on "human error," rather than track defects or aging equipment. In a statement released late Tuesday night, new MTA Chairman Joe Lhota said that that a preliminary investigation indicated that the cause was "an improperly secured piece of replacement rail that was stored on the tracks."

"Storing equipment in between tracks is a common practice employed by railroads across the country to accelerate rail repairs," the statement continued. "The key to this being an effective and safe practice is making sure that the extra equipment is properly bolted down, which does not appear to have happened in this case."

The News reports that a replacement rail was installed Monday night near the site of the crash. According to de Falco, the two suspended supervisors were "responsible for the oversight of the work."

The investigation into the derailment is ongoing.