The MBTA discovered a crack in a rail on the track between Harvard Square and Central Square on the Red Line, slowing travel between the two stations during the busy morning rush hour on Wednesday, according to MBTA spokesman Joe Pesaturo.

Around 10 a.m., Pesaturo wrote to say the problem had been fixed and normal service would be resuming. Shortly after 9 a.m., Pesaturo said that an engineering and track maintenance crew was on scene assessing the situation. The crack was discovered on a northbound, outbound track.

The problem has affected travel times in both directions, with delays rippling throughout the Red Line. 9:19 A.M.