A bomb squad has been called to the new federal building in downtown Oklahoma City after a man caused a disturbance at a security checkpoint.

Officials say the man left a backpack and a threatening note at the building Wednesday afternoon. The man was being questioned by police, and officers were searching the man's car, said Oklahoma City Police Master Sgt. Gary Knight. A bomb squad also has been deployed, but there was no evidence an explosive device has been found, Knight said.

"We're going to make sure everyone is OK and everyone is safe," Knight said. "We want to err on the side of caution.

U.S. Deputy Marshal Kim Heath said the building was evacuated while the incident was investigated.

The federal building opened in 2003 as a replacement for the Alfred P. Murrah Federal Building that was destroyed in the 1995 Oklahoma City bombing.

The new building is just northwest of the former building.