Gunman Prompts Space Center Evacuation

Johnson Space Center security officers and Houston police, including a SWAT team, were dispatched to the scene.

NASA spokesman Bill Jeffs said he could not confirm whether there was a gunman or whether any shots were fired.

"It's an ongoing situation," he said.

Roads within the 1,600-acre campus were blocked off. A nearby middle school also kept its teachers and students inside as the school day ended.

Neither Jeffs nor HPD spokesman John Cannon would confirm television reports describing a gunman and his actions.

Another NASA spokesman, James Hartsfield, said the building was "one of the smaller" office buildings on the JSC campus, where Mission Control is based.

He declined to speculate on how a person would get a gun inside NASA security or what his motives would be.

Christine Reichert, space station flight controller at Johnson Space Center, said employees were being told to stay in their buildings.

She said she people in the building close to Building 44 "were all good. That's all I know."

Doors to Mission Control were locked as is standard procedure.