Updated at 7 p.m. EDT

Amtrak will be restoring rail service between Philadelphia and New York at 5:30 Monday morning, the rail service announced Sunday.

Service between the two cities had been shut down since Tuesday, when train 188 derailed in Philadelphia, killing eight and wounding more than 200.

The affected section of track is part of the Northeast Corridor — the busiest railroad in America.

The fatal derailment occurred when a train was traveling at 106 mph as it entered a curve rated 50 mph, investigators found. Investigators were also looking into reports that the train may have been struck by a projectile shortly before the accident.

Amtrak had shut service down for the remainder of the week while track, signal and power systems were repaired.

Now Amtrak president Joseph Boardman says repairs have been made in "complete compliance" with federal regulators' instructions.

On Saturday, the Federal Railroad Administration ordered Amtrak to take steps to improve passenger safety more broadly throughout the Northeast Corridor. Investigators continue to look into the underlying causes of the derailment.

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