A federal agency has ordered Los Angeles County transportation officials to review whether cutting hundreds of thousands of hours in bus service over the last few years was unjust to riders.

The demand came in a scathing letter Monday from Federal Transit Administration chief Peter Rogoff that discusses “disturbing findings” of a civil rights investigation into policies and practices at the Los Angeles County Metropolitan Transportation Authority.

Those include Metro’s failure to conduct the proper analyses when implementing service changes over the last several years. In the letter, Rogoff chides Metro officials, saying they “should be well familiar with the requirements” because of many years of litigation and a previous consent decree over civil rights issues.