Virginia Tech police chief Wendell Flinchum said that emergency services had received a call at 0715 (1215 GMT) on Monday alerting them to a shooting at the dormitory - West Ambler Johnston Hall.
He said that two hours later there was a second report of shooting, this time at the engineering building, Norris Hall.
Police believed the first shooting may have been a "domestic incident" and that the gunman had left the campus.
After the deadliest shooting rampage in US history, President George W Bush said the US was "shocked and saddened".
"Schools should be places of safety and sanctuary and learning. When that sanctuary is violated, the impact is felt in every American classroom and every American community," he said.
The state university in the town of Blacksburg is home to 26,000 students.