Timeline of Virginia Tech shooting rampage

Gunman opened fire in dorm, then unleashed barrage in second building before dying

SOURCE: msnbc.com; all times are approximate

7:15 a.m.: Gunfire reported

A gunman, apparently carrying two handguns, enters West Ambler Johnston Hall, a coed dormitory that houses 895 people, and opens fire. At least one person is reported killed at the scene. Aimee Kanode, a freshman from Martinsville, Va., tells MSNBC TV that the shooting started on the fourth floor of the dorm. She says a resident assistant knocked on her door about 8 a.m. to notify students to stay put.

9:15 a.m.: Second onslaught

As police are investigating the first shooting, reports of a second shooting at Norris Hall, an engineering building about a half-mile away, are received.

Two law enforcement sources tell NBC News that the a gunman entered the classroom building and chained the doors shut, making it harder for students to get out -- or police outside to get in.

Campus Police Chief Wendell Flinchum later says that the gunman concluded the attack by taking his own life.

9:26 a.m.: E-mail warning

Campus police send out an e-mail warning to faculty and students stating there has been a shooting at West Amber Johnston.

"Police are on the scene and are investigating," it says. "The university community is urged to be cautious and are asked to contact Virginia Tech Police if you observe anything suspicious or with information on the case."

9:50 a.m.: 'A gunman is loose'

Campus authorities issue a second e-mail alert, warning, "A gunman is loose on campus. Stay in buildings until further notice. Stay away from all windows."

10:15 a.m.: Banging heard

Tech student Steve Hanson tells the Associated Press that he was working in a lab in Norris Hall when he heard what he thought was loud banging from construction.

10:16 a.m.: Another alert

Campus authorites issue a third e-mail alert, saying that all classes have been canceled and restating that anyone on campus should "remain where there are, lock their doors and stay away from windows. Persons off campus are asked not to come to campus."

10:52 a.m.:'Multiple victims'

Authorities send out a fourth e-mail alert stating "There has been a multiple shooting with multiple victims in Norris Hall." It erroneously states that police are seeking a "second shooter" and warns that "all people in university buildings are required to stay inside until further notice. All entrances to campus are closed."

Noon: Partial evacuation

Faculty and staff on two sides of the campus are evacuated and told to go home immediately, the Roanoke Times reports.

12:15 p.m.: 'Monumental' tragedy

Virginia Tech President Charles W. Steger reads a statement at a news conference saying, "The university was struck today with a tragedy of monumental proportions." Police Chief Flinchum draws gasps when he announces that at least 21 people are dead.