"A tragedy struck our NASA family today. While we don't yet understand all that's happened, our hearts and prayers go out to the families and coworkers who lost their loved ones today and to the survivor who endured a tragic ordeal."
Editor's 6:23 PM EDT update: The gunman killed a male hostage. A female hostage was bound but not otherwise harmed. The gunman eventually shot himself in the head.
Editor's 6:03 PM EDT update: TV news video shows police freely entering Building 44 - and an ambulance has arrived to treat a wounded person inside Bldg 44. Some news anchors are speculating that this person is the gunman. A Police press conference was planned for 6:00 PM EDT but this has now been delayed.
NASA Update 5:40 pm EDT:
"From the Houston Police news conference at 5:30 p.m. EDT:
One suspect white male, between 50-60 years old, with a handgun is barricaded in a room on the 2nd floor of Building 44.
SWAT Team, with negotiators, is on the scene Police can't confirm whether there are any hostages. No contact has been made with the gunman.
Police has no idea on motive
Police confirmed that two shots were fired and can't confirm whether any individuals has been shot.
Police are working with NASA security to secure the perimeter. Armored vehicles and ambulances are on the scene as a precaution
From JSC's Eileen Hawley Initial communication (email and phone calls) to employees advised them to shelter in place. A second email went out to tell them they could go home at their normal quitting time or if they desired to do so. Our senior leadership will look at this incident to see if anything could have been differently.
Security at other NASA centers currently remains unchanged
Building 44 is a communications & engineering office building with two stories. The building primarily consists of office space and a few labs to support tracking of spacecraft, such as the International Space Station and the space shuttle when it's flying
At 2:40 p.m. EDT, a person with a weapon was reported at NASA's Johnson Space Center Building 44. Johnson Security officers and Houston Police responded to the report and evacuated the building.
There has been no impact to mission control operations.
Police are in charge of securing the scene and any questions regarding their specific activity should be addressed by them.
There are about 10,000 employees (contractor and civil servants) onsite at Johnson Space Center. An additional 5,000 or so work near the facility to support the center
Johnson is a 1600-acre complex"
Editor's note: Suspect: A JSC contractor employee, white male 50 years old, blond hair, 5'9", no facial hair, slim build, light blue shirt and blue jeans. He has barricaded himself inside Bldg 44 in a second floor office. James Hartsfield at JSC is quoted on CNN saying that some shots have been fired. Bldg 44 is in lock down. The rest of the center has now been given an 'all clear'.
Editor's update: CNN just read a KHOU report: a source inside the building told KHOU a meeting was underway. A gunman walked into the room, pointed a gun at one person, and then ordered everyone out of the room. NASA has not confirmed this report.
CNN now reports that SWAT Teams are moving in.