Updated at 5:11 p.m. ET: Police refused to say explicitly that no other gunmen were involved. But they said they were confident that the situation is secure and "you can read between the lines."
Updated at 5:08 p.m. ET: A gunman shot and killed a Virginia Tech police officer Thursday, university officials said. Police said a second person was later found dead.
At a news conference in Blacksburg late Thursday afternoon, police said only that the second body was that of a white male and that he was not shot by police. A weapon was found nearby, they said.
Police said they couldn't officially comment on whether the second person was the gunman, but authorities told NBC's Pete Williams that they believed the second victim was the man who shot the campus officer.
Police said earlier reports that the gunman was the driver of a car the officer had stopped for a traffic violation had turned out to be untrue; instead, they said, the gunman apparently walked up to the scene during the traffic stop and shot the officer.
A campuswide alert was lifted late Thursday afternoon. Montgomery County schools lifted a lockdown and allowed pupils to begin heading home.
University President Charles W. Steger called the incident "an wanton act of violence"
Few students were outside because final exams had been scheduled for Friday and most students were indoors studying, Steger said. Friday's exams were canceled. Counseling and support were being arranged for students and faculty and their families, said Steger, who said the shootings were "very traumatic because of the past."
That was a reference to the deadliest mass shooting in U.S. history, when 33 people, including the mentally ill gunman, were killed on the Virginia Tech campus on April 16, 2007.
The shooting Thursday came the same day as Virginia Tech was appealing a $55,000 fine by the U.S. Education Department in connection with the university's response to the 2007 rampage.
Updated at 4:34 p.m. ET: Virginia Tech has lifted the campuswide alert.
Updated at 4:31 p.m. ET: The Collegiate Times reports that there is now "no active threat" at Virginia Tech and that students are being allowed to "resume normal activities."
Updated at 4:25 p.m. ET: Virginia Tech officials say a weapon was found near the body of the second person who was killed on campus.
Original post: Law enforcement officials tell NBC News they believe the second shooting victim at Virginia Tech University was the man who shot and killed the campus police officer.
NBC's Pete Williams reports that authorities say they're awaiting final confirmation but that they believe the campuswide alert for a gunman at large will soon be canceled.
Msnbc.com's Alex Johnson contributed to this report by Pete Williams of NBC News.