Shuttle buses were deployed to replace service on the MBTA's Red Line due to what the agency described as a medical emergency.
The agency said in a tweet that shuttle buses were replacing Red Line service between Harvard and Alewife stations.
The MBTA earlier tweeted a person was under a train at Davis Square in Somerville, Massachusetts, Monday.
Delays were expected.
This is a developing story and will be updated as more information becomes available.