WASHINGTON, D.C. — The Washington Post reported that Harold Ingram, a contractor, was killed on Sunday in a tunnel explosion while performing maintenance on Washington Metropolitan Area Transportation Authority’s (Metro) Red Line track.

Officials told the paper that the contractor was transported to Howard University Hospital where he later died. Two Metro employees were in stable condition and suffered back-related injuries that Metro said are “serious but considered non-life-threatening.”

Initial reports show leaking hydraulic fluid from an underground vehicle was ignited by welding equipment, causing an explosion and fire. Metro officials also told the Post they were conducting an investigation into the cause of the accident and notified the Tri-State Oversight Committee, which helps oversee the transit agency, and the National Transportation Safety Board. For the full story, click here.