BIRMINGHAM, Alabama - Birmingham police remain on the scene of a suspicious package found early today by a security guard at a downtown building.

Third Avenue North between 20th Street and Richard Arrington Jr. Boulevard has been shut down for a couple of hours while police investigate. Employees at the Massey Building said they were told not to come to work until 8:30 a.m.

Officers have cordoned off about a block, and the police department's bomb truck is on the scene, but there doesn't appear to be any sense of urgency. Traffic is moving normally on 20th and 21st Streets.

It is the second suspicious package found at a downtown building in the past 24 hours. On Sunday, an envelope left at an entrance to the BBVA Compass building in downtown Birmingham resulted in authorities shutting down an area surrounding that building.

In the Sunday incident, the area was shut down for about four and a half hours. Birmingham police determined the envelope did not pose a threat.