Metro officials admitted Thursday that their employees failed to communicate with each other and with riders during the Green Line meltdown that trapped thousands in a tunnel below the Anacostia River, though it said it acted safely.

An internal investigation into the Jan. 30 Green Line incident found that a common mechanical problem escalated into chaos after Metro police did not follow procedures and failed to call Metro’s main command center when they shut down power to the section of track with two trains carrying thousands of riders.