A lockdown on the U.S. Capitol has been lifted after gunshots fired near the building put the area on high alert. According to other reports by staffers and reporters on the Hill, people were told to shelter in place until the order was lifted close to 3 p.m.. There is still significant police activity around the building.

CBS News' Bob Orr reported that a vehicle struck a retaining ballast near 15th St. and Pennsylvania Ave., N.W., one block from the White House. The driver, a woman, Orr was told by his sources, began driving toward the Capitol with police in pursuit. In the vicinity of 2nd or 3rd St. and Constitution Ave., N.E., there were gunshots fired. One person was apparently hit, Orr reported, and there might have been some injuries.

CBS News' Bill Plante said President Obama has been notified.

The Associated Press is citing unconfirmed reports that one police officer has been injured. U.S. Capitol Police will hold a news conference at 3 p.m. at 3rd St. and Constitution Ave., N.E.

According to CBS News' Alicia Budich, an announcement over the Capitol P.A. system said, "Gunfire heard on Capitol Hill. If you are in an office building shelter in place." Budich reported at 2:52 p.m. that people were able to exit the Capitol out of the South Door.

CBS News' Major Garrett also reports that that the section of Pennsylvania Ave. in front of the White House has been closed off. U.S. Secret Service told CBS News it was shut down in response to the reports of a shooting.