The student who killed 32 people in America's worst ever university shooting incident at Virginia Tech University sent a package to the US TV network NBC News on the day of the shootings, police officials have told.

It has now emerged that the two-hour gap between the shootings was the time Cho Seung-hui used to post the haunting package to the news station.

NBC said that the package contained "disturbing" photographs, video and writings, with the video showing Cho angrily wielding guns and pointing them at the camera.

On the video Cho said: "You had a hundred billion chances and ways to have avoided today.

"But you decided to spill my blood. You forced me into a corner and gave me only one option. The decision was yours. Now you have blood on your hands that will never wash off. I didn't have to do this. I could have left. I could have fled. But now I will no longer run."