Thirty-three people, including the gunman, were killed at a Virginia university Monday in the deadliest mass shooting in U.S. history. At least 15 other people were injured, some of them as they leaped to safety from the fourth floor of a classroom building.

The shootings, which took place in two locations on campus, came just four days before the eighth anniversary of the Columbine High School bloodbath near Littleton, Colo. They created panic and confusion at the college, where students and employees angrily asked why the first e-mail warning did not go out to them until the gunman had struck a second time.

Federal law enforcement officials said the gunman killed himself after he shot dozens of people at Virginia Polytechnic Institute and State University in Blacksburg, in southwest Virginia. Thirty-two people plus the shooter were confirmed dead.

In addition to the 33 dead, hospitals reported that 15 people were injured, some of whom had jumped from the fourth floor of the classroom building where the second wave of shootings took place. Five were in stable condition; the conditions of the others were not immediately reported.