CHICAGO (WGN) The Dirksen Federal Courthouse in Chicago and its surrounding streets are back open Wednesday morning after a knife-wielding man entered the lobby Tuesday and demanded to speak to the FBI, forcing a building evacuation and a lengthy standoff with police.

For nine hours Tuesday, according to authorities, a man wearing a backpack and holding a large knife to his neck paced around the lobby of the building. Employees received the first emergency alert just before 11 a.m., and surrounding streets were blocked off during the ensuing standoff and investigation.

The incident was resolved by Tuesday night, but police have not released the name of the man taken into custody or a possible motive behind his actions.

A federal law enforcement source said a man carrying a backpack walked into the public side of the lobby late Tuesday morning, asking to talk to several people. He then pulled out a knife and held it to this throat while asking to speak with the FBI, according to sources.

As the roads were shut down, agents broke into and searched a 2008 Chevrolet Impala with Nebraska plates parked along Jackson Boulevard. After the vehicle was cleared by federal agents, it was hauled away on a flatbed.

A source within the building told WGN News the building was never on lockdown and employees were directed initially to avoid the lobby. Just before 3 p.m., however, law enforcement reportedly called for a mandatory evacuation of the building. U.S. Marshals also helped escort employees out of the courthouse.

FBI negotiators were also spotted at the scene.

At around 7 p.m. Tuesday, the man was seen repeatedly putting a sign to the window that read, “call lawyer.” He also appeared to have two other signs, one that read “bring lawyer” and another that read “no body cam?”

Just after 8 p.m., a large group of federal agents rushed into the building. A stretcher was also brought inside, and the man was brought out with a bandage on his neck, although it was not clear if he sustained a wound from the knife he was carrying.

Federal law enforcement sources told WGN-TV agents with the U.S. Marshals Service were able to tase the man and secure the scene with help from other federal agents.

Sources said the situation was resolved without incident.

The incident left many people who work nearby concerned.

“I get kind of a nervous feeling, given these are federal buildings and given everything that’s going on in our country already,” Stephanie Mabry, who works nearby, said. “So it makes me a little uneasy.”