HOUSTON -- A gunman shot a hostage and then himself while barricaded inside a building at Johnson Space Center for nearly four hours on Friday, KPRC Local 2 reported. A second hostage was found duct-taped to a chair but was unharmed, according to authorities.

Officials said the situation started at about 1:40 p.m. when reports of shots fired came in and a man with a gun was spotted inside building 44, which is the communications and tracking development laboratory, an engineering building.

Authorities said the man with a revolver barricaded himself in a second-floor office.

Capt. Dwayne Ready of the Houston Police Department said a male hostage was shot when the gunman initially fired two shots in the building.

"The report to us was that there were two shots and that's what caused us to respond to this scene, and we're believing that one of the hostages -- the male who's deceased -- was shot during that particular moment," Ready said.

Ready said communication was not established with the gunman, identified as 60-year-old Bill Phillips, despite repeated efforts. SWAT officers moved in at about 5 p.m. when they heard a third shot.

They found Phillips dead from a shot to the head and a male hostage, identified as David Beverly, dead from a gunshot wound to the chest.

Phillips was a contract worker employed by Jacobs Engineering Group Inc.. He and Beverly were engineers in the lab. Beverly was employed by NASA.

The shooting was the result of an argument between Phillips and Beverly, officials said, but details were not known.

Phillips was described as a good employee who had worked at NASA for more than 12 years. He was single without children.

NASA issued the following statement.

"All of us at NASA are profoundly saddened by today's tragedy at the Johnson Space Center in Houston. Our hearts go out to the families of the victims and all those touched by today's events."

NASA is a secured facility that requires approved access.

"If you are an employee and have the correct badge and the correct sticker on your car, you can generally drive right in," former astronaut Dr. Bill Fisher said. "If this were a contractor or a NASA employee, that person would have almost unlimited access to the Space Center once you're through the gate. For someone who is not a NASA employee, they have to go through a number of security checks and they would have to get a special badge."

JSC employees were initially informed about the gunman via e-mail and asked to shelter-in-place. A second e-mail told employees that the situation was confined to one building and they were allowed to go home, according to Eileen Hawley, with NASA.

Johnson Space Center is located on NASA Parkway in Clear Lake.

Building 44 was described as "one of the smaller" office buildings on the JSC campus, where Mission Control is based.

Space Center Intermediate School, located at 17400 Saturn Lane, was placed in lockdown as a precaution. The lockdown was lifted by 3:45 p.m.

Background Of Johnson Space Center

Johnson Space Center was established in 1961 as the Manned Spacecraft Center and, in 1973, renamed in honor of the late President and Texas native Lyndon B. Johnson.

JSC has served as the nerve center for the Gemini, Apollo, Skylab, space shuttle, International Space Station and other programs.

About 3,000 employees people work at the center; most are engineers and scientists.

More than 12,000 contractors from about 50 companies work onsite or in nearby office buildings and other facilities.

There are about 110 astronauts based at JSC for training.