Two Pentagon police officers were shot at the subway entrance to the military complex around 6:40pm Thursday evening.

The suspect walked up to the entrance and opened fire. He hit the two officers, who fired back and hit the suspect. All three were taken to hospital, but injuries are said to be non-life threatening.

In the aftermath, a security lockdown was imposed and all Pentagon entrances were secured. Since the September 11, 2001 terrorist attacks, riders can no longer enter the building directly from the subway. They take a long escalator to the surface then pass through two security checkpoints.

An investigation is underway. It’s not clear why the suspect opened fire on the officers.