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DEVELOPING: PITTSBURGH -- An armed man who took a hostage inside a downtown Pittsburgh office building has surrendered to police.

Police Chief Nate Harper says the suspect gave himself up after posting Facebook updates in the early hours of the standoff saying he had "lost everything." Harper says the hostage is OK.

Police identified the hostage-taker as Klein Michael Thaxton. Harper had said Thaxton had a military background and was suicidal.

The standoff began Friday morning inside the 16th-floor office of a benefits administration firm.

Harper says Thaxton was cooperative but made no demands.

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Thaxton's friends had responded to his Facebook posts by urging him to end the situation peacefully, including one who asked him to think of his mother.

The Facebook page was later taken down.

This is a developing story. Refresh for updates. Earlier version of story is below:

An armed man with a military background took a hostage inside an upper floor of a downtown Pittsburgh office building on Friday and posted Facebook updates saying he had "lost everything."

Police Chief Nate Harper identified the hostage-taker as Klein Michael Thaxton, who wrote on Facebook that people will "never have to woryy (sic) about me again" after he took a man hostage inside the office of a benefits administration firm on the 16th floor of Three Gateway Center.

Harper said Thaxton had been cooperative, although he has made no demands.

Thaxton's friends responded to his Facebook postings by urging him to end the situation peacefully, including one who asked him to think of his mother.

The Facebook postings have the potential to both help and harm the negotiations, Harper said.

It's helpful that Thaxton can see "that people are concerned about his well-being," Harper said, but "it is a distraction for negotiating."

Harper noted that Thaxton remains calm and they want to keep him that way.

Workers milled around near the building after they were ordered out shortly after 8 a.m. when employees in a nearby office called 911 to report an emergency at CW Breitsman Associates. It's not clear what led Thaxton to target the company, which runs employee-benefits programs for other businesses.

Police brought the suspect's mother to the office building and put her in touch with Thaxton, Harper said. She said she doesn't know what drove her son to take a hostage, he said.

A worker on the 16th floor described a woman running into her office yelling for someone to call 911. Kathi Dvorak, an administrative assistant at AXA Advisors, said a second woman ran in and said her office was being robbed.

Harper said authorities know the name of the man taken hostage, but he did not release it. He had previously described the hostage-taker as having a military background but didn't elaborate.

Thaxton has a criminal record that includes a guilty plea to robbery earlier this year and a minimum six-month jail sentence.

Joel Kirchartz, a 28-year-old web developer who works on the 17th floor, said he and his co-workers looked out the windows Friday morning and "a bunch of cops pulled up with all sorts of sirens going; there must have been 20 of them." He said he went downstairs to find out what was happening and by the time he got outside, police had sealed the building.

Another worker, Sarah Vereb, said she was at her desk when she was ordered to leave the building shortly after a friend called to report that she wasn't being allowed up from the lobby.

Hundreds of workers walked down the stairwell. Vereb said the exodus was orderly and "very, very quiet."

A phone message left for the building's Santa Monica, Calif.-based ownership group was not immediately returned. The building complex management office confirmed the evacuation and said it was working with police.