Police have identified the armed man who took a hostage inside an upper floor of a downtown Pittsburgh office building on Friday, forcing police to evacuate the high-rise.

Authorities say Klein Michael Thaxton took the hostage shortly after 8 a.m. on the 16th floor of Three Gateway Center, one of six office buildings that dominate the city skyline, Pittsburgh Police Chief Nate Harper told reporters.

According to Harper, Thaxton, a man in his 20s with a military background, entered the offices of CW Breitsman Associates, a firm that runs employee-benefits programs, and asked for the man he took hostage.

While Thaxton is said to be in possession of a weapon, Harper described the suspect as cooperative. No demands have been made at this time.

"His demeanor right now is calm and he's not being irrational," Harper said.

Reports are also surfacing that indicate Thaxton is  posting Facebook status updates in the midst of the situation.

Some updates from the alleged suspect say that he "lost everything," while others read, "never have to worry (sic) about me again."

According to the Associated Press, 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.

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

Reports from earlier in the day indicate that workers circled the area near the building after they were ordered out shortly after 8 a.m. A worker on the 16th floor described a woman running into her office and yelling for someone to call 911. Kathi Dvorak, an administrative assistant at AXA Advisors, told reporters a second woman ran in and said her office was being robbed.

It's not clear what led Thaxton to target the company, which runs employee-benefits programs for other businesses.

Joel Kirchartz, a 28-year-old web developer who works on the 17th floor, told reporters 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.

No injuries or casualties have been reported at this time.