A power failure that put the brakes on thousands of early morning commutes is over, Amtrak officials say.

The outage happened just after 8 a.m. when Amtrak?s Northeast Corridor lost power, bringing trains to a halt from New York City to Washington D.C. It stopped some trains in tunnels and forced many commuters to find new routes to work.

Amtrak workers have yet to find where the outage originated or why it crippled the Northeast power grid.

Rail service on the Northeast Corridor was restored after the outage.