SOT Chief Nate Harper, Pittsburgh police: " -------------------------BC-US--Office Building-Hostage Call, 5th Ld ,Pittsburgh police: Man holds hostage in high-risePittsburgh police: Armed man holding at least 1 hostage in high-rise office towerAssociated Press= PITTSBURGH (AP) _ Pittsburgh's police chief says authorities are negotiating with an armed man who has taken at least one hostage in a downtown office building. Police say the man entered the building sometime after 8 a.m. Friday and went up to a 16th floor office suite inside Three Gateway Center. Chief Nate Harper says the man took at least one hostage _ possibly two hostages _ inside a business after entering the suite and asking about a particular person. A witness who works on the 16th floor identified the business where the hostage situation was unfolding as CW Breitsman Associates, a firm that helps businesses run employee benefits programs. Harper says no shots have been fired and no injuries are reported. Several hundred people milled around about a half-block from the 24-story building after police evacuated it.(****END****) VIDEO PRODUCER: NICOLE GRETHER---------------------------VIDEO SOURCE: WPXI-----------------------VIDEO APPROVAL: David Bruns----------------------------VIDEO RESTRICTIONS: Courtesy WPXI-TV; Embargo Pittsburgh----------------------------------MARKET EMBARGO (S): Pittsburgh--------------------------------SCRIPT/WIRE SOURCE: BC-US--Office Building-Hostage Call, 5th Ld