A Virginia Tech police officer was fatally shot Thursday during a routine traffic stop on the Blacksburg campus and a second person was found slain in a nearby parking lot after the gunman fled, the university reports.

NBC News, citing law enforcement officials, is reporting that the person found dead in the parking lot is the gunman who killed the officer. University officials are expected to update the media at 4:30 p.m.

The university said on its Twitter account at about 4:30 p.m. that there no longer was a threat on campus and it lifted an afternoon-long lockdown.

Earlier, a campus-wide message warned students, “Stay indoors. Secure in place.”

There are no classes today at the university, as students have a reading day to prepare for finals, which were to begin Friday. University officials postponed Friday’s exams.

The university said on its Web site that a routine traffic stop prompted the shootings.

Jermaine Holmes, director of academic support services for student athletes, said the shooting appeared to be a traffic stop gone awry.

“It’s right across from our building in the parking lot,” he said. “It didn’t appear to be just a kind of random shooting.”

Holmes said the parking lot had been cordoned off with yellow police tape, and the area was thick with officers. He said he and his colleagues felt safe, and he was impressed by the swiftness of the campus alert system.

“The facilities folks locked down the building immediately,” he said. ”We’re not allowing any students or staff to leave.”

The second body was found in a parking lot a short distance away from the original shooting, in the direction the gunman fled.

Virginia Tech, a public campus of about 30,000 students, has one of the nation’s most advanced security alert systems, installed after the nation’s worst campus shooting, a 2007 rampage by student Seung Hui Cho that left 33 dead, including the shooter.

University officials were criticized for taking too long to lock down the campus that day and have dramatically overhauled their alert system. The entire campus was on lockdown Thursday.

In 2007, though, there was a two-hour delay from the discovery of Cho’s first two victims to the first e-mail alert to campus. Thirty others were killed in between, in an academic building.

But on Thursday, alerts went out by e-mail, text-message, electronic message boards in classrooms and audible alarms on campus within minutes of the gunshots. Virginia Tech’s emergency response protocols are considered a model for other schools.

“We deployed them all, and we deployed them immediately,” said Mark Owczarski, university spokesman, at a news conference.

The shooting happened, by chance, on a day when Virginia Tech officials were in Washington to appeal a $55,000 federal penalty from the U.S. Department of Education over the university’s response to the 2007 massacre. Virginia Tech Police Chief Wendell Flinchum was among the scheduled witnesses, according to a report in the Roanoke Times newspaper.

Today’s report of shots fired came in the noon hour. The first alert advised of gunshots reported at the school’s Coliseum parking lot, off Washington Street and Spring Road, in a southern section of campus devoted to athletics. It told the community to stay inside and secure doors.

A second alert described a suspect as “white male, gray sweat pants, gray hat w/neon green brim, maroon hoodie and backpack,” and said he was “on foot towards McComas,” a facility housing health and counseling services.

Matt Banfield, a senior from Williamsburg who is a representative on the board of visitors, said shortly after 3 p.m. that hundreds of students were still waiting in the Squires Student Center on lockdown.

People were calm, he said, watching the news and checking their phones, or listening for updates from staff members. “The way the university staff is handling this … has been very comforting.” They’re handing out bottles of water and giving constant updates, he said.

Students were alerted by the university in many ways, he said, including e-mails, phone calls, texts, Web site updates, and scrolling messages on the clocks in all the buildings. He feels safe, he said. “It is unfortunate that because of our past, I think people think that stuff like this happens here all the time. This could happen any place. I feel no less safe now than I have at any other point here.”

Ankit Ahuja said he was among several dozen students studying at Newman Library when the campus was locked down. Told to stay away from the windows, students were staying calm and watching television for news updates, he said.

“I’m just thinking about the repercussions of this,” he said. “I think for the next few weeks they’ll have stricter security on campus.”

A 23-year-old graduate student from New Delhi, Ahuja said he chose Virginia Tech because of its reputation for high-quality research in his field, computer science. He knew about the 2007 shooting, but it didn’t concern him.

“That was a one-off incident,” he said. “It could happen anyplace.”

Shawn Ghuman, a sophomore at Virginia Tech from McLean, said that he got the first alert about the gunshots when he was in the dining hall next to his dormitory, Harper Hall, on the west side of campus near where the first shots were fired. And by the time he went outside to go back to his room, he said the campus already looked empty. “They did a really good job keeping us alerted and telling everyone to stay indoors,” he said

The alerts go out via e-mail, text and robocall, he said.

Students are in the middle of finals this week, and he has been going to study sessions. From the third floor window of his dorm, he can see police cars and TV trucks.

I’m nervous about our reputation,” he said. “Tech’s a great school.”

Freshman Miles Curley, 19, of Rock Hill, S.C., said he was leaving his dorm, Cochrane Hall, when he received a text message alert about the shooting. He had been headed for his car parked nearby in the Coliseum lot, where shots were fired.

Curley said he immediately returned to his room, where he could hear sirens. He’s been checking Twitter and television news since then, he said, and fielding phone calls and texts from worried friends and family.

“It’s what happened in ’07 — it’s kind of crazy to think that something even close to that would ever happen again,” Curley said. “I’m praying for anyone who’s affected.”

Freshman Matthew Spencer was walking to a bus stop about 12:30 or 12:45 p.m. when he saw police running and driving by and paramedics running to an area near the bus stop. There’s a large parking lot between the stadium and McComas Hall, where students work out, he said. At least 10 police cars were in the area around Washington Street and the basketball arena, he said. That’s when he got the alert from the university to get inside.

About 1:45 p.m., he saw officers racing to another part of campus. “At least 15 police and undercover cars took off on Washington Street and headed towards the town and or that side of campus where Torgenson Bridge is,” he said.

“Everyone in the hallway is freaked out and stuff,” he said. He was in eighth grade when the mass shooting happened. “I lived in Christiansburg during the massacres, so it’s kind of scary.”

Virginia State Police, as well as campus and local police, are searching for the gunman.

Staff writers Emma Brown, Michael Alison Chandler, Tom Jackman and Susan Svrluga contributed to this report.

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