Three people were wounded in a shooting incident at a Metro station near the Pentagon Thursday evening. The military locked down the complex after the shooting.

Two Pentagon police officers and a suspect were shot in the incident. The wounded officers are with the Pentagon Force Protection Agency, according to Chris Layman, spokesman for the agency. He said they have one suspected shooter in custody.

Police chief Richard Keebill told reporters the suspect is an American. He showed no emotion nor distress as he walked up to the main entrance of the Pentagon at around 6:40 p.m. (2340 GMT) and opened fire.

"He looked very cool," Keebill said.

The male suspect shot two officers, both of whom sustained non-life-threatening injuries. The officers fired back, wounding the suspect, whose condition is unknown.

The injured were later taken to the George Washington Hospital in Washington, DC, just across the Potomac river from Pentagon.

After the shooting, the Pentagon was locked down, with all entrances to it closed, and no people were allowed in or out. CNN said FBI agents were seen at the scene.

Local TV showed armed police were sweeping through the shooting scene, searching for other possible suspects.

All Pentagon entrances are now reopened except the Pentagon Metro entrance. The incident is still under investigation, according to a statement on the Pentagon website.

Pentagon is a huge, five-sided office complex in Arlington County, Virginia, just outside Washington, DC. The building houses U.S. Defense Department.

The Pentagon is the world's largest office building by floor area. On Sept. 11, 2001, a hijacked American airliner crashed into the western side of the Pentagon, killing 189 people, including 64 people aboard the plane and 125 working in the building.