D.C. firefighters and emergency responders may not have been able to communicate effectively during last week's fatal L'Enfant Plaza smoke incident because of recent changes to a communications control room in Northwest D.C., according to multiple sources with direct knowledge of the investigation.

The D.C. Fire Department recently made a move to encrypt its radio transmissions, meaning only agencies that know how to tap into the encrypted network can communicate with D.C. Fire and EMS units.

On Jan. 12, the day of the L'Enfant Plaza episode, Metro's communications controls were not synced up with D.C. Fire's communication controls in the new encrypted setting. Those controls are housed at a control room at One Judiciary Square, NW.

"D.C. Fire changed the configuration." A source with direct knowledge of the situation tells News4.

Whether or not Metro should have known that the configuration was changed was not immediately clear, but the fact that the controls in that room were not in the correct position means D.C. Fire radios could not communicate correctly.

Poor communication could have delayed getting help to passengers, who have said they were stuck in the smoke-filled train for more than half an hour.

One woman, 61-year-old Carol Glover, died in the incident. The Office of the Chief Medical Examiner ruled her death accidental by acute respiratory failure from smoke exposure.

"The communication is, of course, very important," D.C. Mayor Muriel Bowser said during a press conference last week when asked about D.C. Fire's new move to an encrypted network. "I don't have any reason to think that the encryption has anything to do with it (but) we've heard reports that some of our first responders switched channels and were able to hear more clearly."

The D.C. Firefighters Union has spoken out against plans to move the D.C. Fire communication system to an encrypted network. Other local fire agencies expressed their concern with being able to communicate seamlessly with that kind of network.

On Wednesday afternoon, congressional leaders as well as Metro and NTSB leaders will go behind closed doors to hash out what happened a week ago at L'Enfant plaza.

One of the main topics that will be talked about is the breakdown in communication. The issue of encryption is expected to be a focal point.

News4 is among the media outlets that has asked law enforcement not to encrypt radios, so we can quickly alert the community about potentially dangerous or threatening incidents.