(UPDATE 12:49 p.m. ET)
The Capitol Police have alerted Senate staffers the situation involving a suspicious package has been resolved.
"The U.S. Capitol Police have removed the suspicious package from the Hart Senate Office Building and the envelopes from the third floors of the Hart and Russell Senate Office Buildings. The areas are now open," the agency wrote in an email.
(UPDATE 12:24 p.m. ET)
Authorities are investigating a suspicious letter at the office of Sen. Carl Levin in Saginaw, Michigan. "Earlier today, a staffer at my Saginaw regional office received a suspicious-looking letter," Levin said in a statement. "The letter was not opened, and the staffer followed the proper protocols for the situation, including alerting the authorities, who are now investigating. We do not know yet if the mail presented a threat."
(UPDATE 12:08 p.m. ET)
The man carrying a bag of letters who is being questioned by Capitol police is not believed to be connected to a letter possibly containing ricin found in a Senate mailroom and an apparently similar letter sent to President Obama, a federal law enforcement official told CNN. The man being questioned is described as emotionally disturbed, the official said.
(UPDATE 12:00 p.m. ET)
Capitol Hill Police are questioning a man with a backpack in the area of the Hart Senate Office Building. He raised suspicions with the contents of his backpack and the way he responded to police questions, two Capitol Hill police officers told CNN. The man's backpack contained sealed envelopes, one of the officers said. The backpack is being X-rayed, one of the officers said.
(POSTED 11:43 a.m. ET)
U.S. Capitol Police are evacuating the first floor of the Hart Senate Office Building due to a suspicious package. People on other floors of the building are being told to go into their offices. Separately, there is a suspicious envelope at the office of Sen. Richard Shelby of Alabama, in the Russell Senate Office Building. Security has cleared the hall but is not officially evacuating.