Pentagon security officer knew something was about to happen based on look on shooter's face

[Jenna]

Pentagon security officer Marvin L. Carraway Jr. saw the man walking toward him. A split second later, he saw the man's gun. "When I looked at the shooter, he looked at me and I recognized a certain look on his face," said Carraway. "Once I saw that, what went through my mind -- 'This is it, something's about to happen.'"
Authorities say John Patrick Bedell arrived at the Pentagon late Thursday with two 9 mm semi-automatic weapons, at least as many magazines, and a vendetta. The 36-year-old had driven from California to Washington wearing a suit and a calm look. He could have passed for any tourist or worker who went through the security checkpoint every day on the way into the Pentagon.
Officer Colin Richards, who mans the booth with Carraway, looked up to see Bedell point his gun at his colleague and fire.
"The shooter was so close," Richards recalled. "I was surprised he missed. I thought he hit Officer Carraway or hit me."
"There was a lot of chaos," said Carraway, a former Marine, who was grazed by Bedell's bullets and suffered minor injuries.

Officer Jeffrey Amos was manning an exit area a few strides away. Also a former serviceman, he recognized the popping sound of gunfire and ran toward it. Amos took a bullet in his shoulder, but he and Carraway kept their focus.
They fired. Bedell went down, hit with a fatal shot to his head.

More here: Pentagon security officer knew 'something's about to happen' - CNN.com

[Captain America]

Excellent job of picking up on non-verbal clues and not ignoring the hairs when they stand up on the back of your neck.

[lewisipso]

It's a recognition that most people would not pick up on. Excellent job on that and apparently shot placement. That's gun control.

[WyomingSunrise]

Good job. Always trust your gut