Armed man holds hostage in Pittsburgh, while posting on Facebook By Drew Singer PITTSBURGH (Reuters) - An armed man was holding a hostage inside a Pittsburgh high-rise building on Friday, authorities said, and he appeared to be posting messages about his situation on Facebook. Police were negotiating with the man who said he had a gun and also a bomb in a 16th-floor office at 3 Gateway Center, Pittsburgh Police Chief Nate Harper told reporters at the scene. "He is not telling negotiators why he's doing this," Harper said. There have been no injuries, he added. Police identified the man as Klein Michael Thaxton and said they were talking to him by telephone and monitoring his Facebook page. On Facebook, a man who appeared to be Thaxton was posting messages at mid-morning. He also posted what he claimed was his telephone number. "how this ends is up to yall," said one of his Facebook messages. In another message, he wrote: "i cant take it no more." "this life im livn rite now i dnt want anymore ive lost everything and i aint getting it back," said another message. Several people responded to him on Facebook saying they were praying for him and encouraging him to cooperate with police. But others were urging him to continue his standoff with police, Harper said. Police were monitoring those Facebook messages and those people could face criminal charges as accessories, he said. Police said they were considering asking Facebook to take down Thaxton's page and as of early afternoon, it was no longer available. Thaxton walked into the office shortly after 8 a.m. and took one man hostage, police said, but had not made any demands. Harper said Thaxton was being cooperative and calm and that police were willing to be patient in resolving the standoff. "We might be here for a while," Harper said. Thaxton's mother was escorted inside the building to talk to her son, but she told police did not know his motive, Harper said. As she left the building, she was visibly distraught. "I just want him to get the help he needs," she said, refusing to give her name. The incident was taking place in the office of a company that handles union pensions, but police said Thaxton did not appear to have any connection to the company. On Facebook, the man believed to be Thaxton also wrote: "welln pops youll never have to worry about me again you'll nevr need to by me anything no need to ever waste ur hard earned money on me. i'll live n jail you dnt want me around anymore thats kool bye..." Police said the suspect was believed to be ex-military, and Thaxton's mother confirmed that her son had served in the U.S. Army. The situation was contained and rest of the office building was not evacuated, Harper said. Police cordoned off several streets around the office building. Additional reporting by Matthew Keys; Writing by Ellen Wulfhorst, editing by Jackie Frank