An armed man claiming to have a bomb has taken a hostage in an office block in Pittsburgh, Pennsylvania.
Pittsburgh police say they are trying to negotiate with a man armed with a gun, who says he has a bomb on the 16th floor of 3 Gateway Center, Downtown, Pittsburgh.
Special weapons and tactics officers have arrived at the scene and his mother has been brought in to talk to him.
Police say he walked into the suite and declared that he had a gun and a bomb. He took a manager hostage and told everyone else to leave.
Chief Nate Harper said: "There have been no injuries and the hostage is believed to be the man's intended target.
"He's being very cooperative at this time. He is negotiating with our negotiators."
The incident is taking place in the office of a company that handles union pensions.