LISTEN: Scanner Traffic Response To Oregon Mass Shooting

CHICAGO (CBS) -- Listen to the scanner traffic as authorities respond to a mass shooting at a community college in Oregon.

Based on the recordings, a man entered a classroom at Snyder Hall at Umpqua Community College in Roseburg, Ore.

He exchanged gunfire either inside or near the classroom, "on the southeast side of Snyder Hall."

After a few minutes somebody is heard saying, "Code 4 .. suspect is down."

Later: "Respond with as many ambulances as possible ... up to 20 victims."