A federal courthouse was locked down for more than two hours Thursday and its courtrooms sealed after a suspect fled from U.S. marshals inside the building.

Officers searched floor-by-floor but said they didn't find Larnell Rogers. They reopened the building around 2 p.m. and said Rogers was still at large.

Rogers had been accused of lying to an ATF agent and was scheduled to appear in court but fled after learning the judge had issued a warrant for his arrest, U.S. Marshals spokesman Kim Widup said.

Authorities instructed court officials to lock all doors in the Everett M. Dirksen Federal Building "out of an abundance of caution," Widup said.

Rogers apparently showed up late for a hearing, prompting U.S. District Judge Samuel Der-Yeghiayan to issue the bench warrant.

"Once he (Rogers) was in the building, somebody said, 'Hey they want to see you, you're wanted now,' and then he decided to run away within the building," Widup said. That sparked the lockdown and search for Rogers, who Widup described as "nonviolent".

The 28-story glass-and-steel federal building is on the south side of Chicago's downtown Loop and has metal detectors and security at its entrances.