Engineering firm tweets from inside the Navy Yard lockdown [photo]

Police and guards running around the Washington Navy Yard. Unsure of what's going on.

— Tridentis (@Tridentis) September 16, 2013

Reports of a shooting inside building 197 of the Washington Navy Yard. Shelter inside

— Tridentis (@Tridentis) September 16, 2013

Washington Navy Yard still on lock down. Hearing that there were multiple shootings at NAVSEA

— Tridentis (@Tridentis) September 16, 2013

US Navy is saying it's still an active shooter

— Tridentis (@Tridentis) September 16, 2013

Shooting inside NAVSEA building 197, Washington Navy Yard. Stay safe!

— Tridentis (@Tridentis) September 16, 2013

On lock down at the Navy Yard sitting with engineers from blg 197. Watching the news describe what we do in that building.

— Tridentis (@Tridentis) September 16, 2013

At least 5 shot.

— Tridentis (@Tridentis) September 16, 2013

We still have an active shooter at the navy yard. You should not be walking around.

— Tridentis (@Tridentis) September 16, 2013

Reports that the FBI is on-site at the navy yard. Seems very strange.

— Tridentis (@Tridentis) September 16, 2013

@theHillisHome we are on-site and reporting the best we can.

— Tridentis (@Tridentis) September 16, 2013

Reporting that the shooter used a shotgun inside building 197 seems wrong. You can't even get a cell phone in that building.

— Tridentis (@Tridentis) September 16, 2013

Makes sense RT@amitalkincrazy: @Tridentis The reports we're hearing outside is that the shooter used an AR. Security was the 1st to be shot.

— Tridentis (@Tridentis) September 16, 2013

Officer just informed us that they have the shooter trapped in a building. We don't know which one though.

— Tridentis (@Tridentis) September 16, 2013

Sweeping the navy yard. http://t.co/Zjox3XNi6R

— Tridentis (@Tridentis) September 16, 2013

All of our employees are accounted for and safe.

— Tridentis (@Tridentis) September 16, 2013

Sad day RT @KevinMercuri: Four killed, eight wounded at the Navy Yard in Washington, DC, according to @NBCNews Jim Miklaszewski

— Tridentis (@Tridentis) September 16, 2013