CNN) — A lone gunman is dead after police said he killed at least 21 people Monday during twin shootings on the Virginia Tech campus — the worst school shooting incident in U.S. history.
"Some victims were shot in a classroom," university police Chief Wendell Flinchum said during a news conference in Blacksburg.
Police believe there was only one gunman, Flinchum said.
• NEW: Four hospitals report 29 wounded
• Police chief says at least 22 people are dead, including gunman
• Attacks mark deadliest school shooting in U.S. history
• Student describes situation as "mayhem"; says 2 students jumped from window