A Virginia Tech police officer was slain and a second person was later found dead near the university's stadium. Authorities believe the gunman is the second fatality, and a weapon was recovered near his body. A lockdown was lifted hours later.

Update at 7:12 p.m. ET: The candlelight vigil originally announced for 8 p.m. tonight has been rescheduled for Friday at 6:30 p.m., the Collegiate Times says.

Update at 6:39 p.m. ET: Virginia Tech announces that the final exams schedule will resume Monday. Friday exams were canceled.

Update at 5:58 p.m. ET: USA TODAY's Marisol Bello has more details, these provided by campus spokesman Larry Hincker:

The first calls reporting the shooting came into dispatch at around 12:30 p.m. At 12:36, dispatch issued its first alert, which went out by text messages, e-mail, the university's website, Twitter and the public-address system, which broadcast the alert campuswide. He said the university sent out six alerts while the campus was on lockdown.

Update at 5:53 p.m. ET: A candlelight vigil is to begin at 8 p.m. ET at the memorial to the 2007 mass shootings.

Update at 5:47 p.m. ET: USA TODAY's Marisol Bello fills in details of today's shooting from Gene Deisinger, Virginia Tech deputy chief of police:

At 12:15 p.m., a four-year veteran of the police force made a traffic stop near the coliseum. About 15 minutes later, witnesses called dispatch reporting that a white male walked up to the officer and shot him. The man then ran off in the direction of a nearby parking lot. Police responding to the call saw a suspicious male near the parking lot and when they went to approach the individual, they found him dead. A weapon was found in the area. Police would not say what type of firearm was found. Investigators do not believe that the driver of the car involved in the traffic stop was involved. Police would not say if the second person was the shooter. "I believe investigators are confident we've located the person," said Sgt. Robert Carpentieri, spokesman for the Virginia State Police, which is leading the investigation. "I won't specifically address that but you can read between the lines." "It's a matter of confirmation," said university spokesman Larry Hincker.

Officials still have not released the names of the dead.

Update at 5:36 p.m. ET: The Collegiate Times offers this series of tweets as the most-up-to-date version of today's shooting:

Police officer was killed by a man in Coliseum Lot while making a traffic stop on an unrelated car. Then the suspect fled on foot in the direction of the cage lot near Duck Pond. Police sighted suspicious man in the cage. When police made further efforts to make contact with the suspicious man, they found him dead. A weapon was also found at that scene. Police are not confirming identities of either dead person, other than to say first was a member of VT Police.

Update at 5:08 p.m. ET: A weapon was recovered with the second body, a male, the university is reporting. There are no other victims.

Update at 4:59 p.m. ET: The Virginia State Police say the suspected gunman was not the person pulled over during traffic stop, the Associated Press reports.

Update at 4:40 p.m. ET: Virginia Tech says via Twitter that law enforcement agencies "have determined there is no longer an active threat or need to secure in place. Resume normal activities."

Update at 4:27 p.m. ET: NBC News is reporting that law enforcement officials believe the Virginia Tech gunman is dead, the second victim of today's shooting.

The lockdown is expected to be lifted shortly.

Initial posts by Douglas Stanglin:

Update at 3:06 p.m. ET: Virgina Tech says Friday's exams have been postponed.

Update at 2:44 p.m. ET: Mark Owczarski, director of news and information for the university, the gunman is still at large and that students should remain indoors.

"The status of the shooter is unknown," Owczarski told a news conference. He says there are many law enforcement agencies on the scene and "we are looking absolutely everywhere."

LIVE: Webcam at Va. Tech

Owczarski says the police officer who was killed was a campus officer. He says the identity of the second victim has not been determined.

He says the shooting occurred during a traffic stop at the Coliseum Parking Lot. He says witnesses saw the officer being shot at that location. Owczarski says the shooter fled on foot and headed toward Cage, a student parking lot. Police responding to the initial shooting found the second victim dead at the second location.

Owczarski says most students were indoors today studying for exams that begin Friday.

Update at 2:34 p.m. ET: A SWAT team is now outside the Squires Student Center at the heart of campus. The Collegiate Times newspaper says on its Twitter feed that its staff has been evacuated from its office at the student center and that students are being moved to a "secure room" in the Student Center.

Update at 2:28 p.m. ET: Virginia Tech says on Twitter reports of shots fired at other locations around campus after the initial incident are unfounded.

Update at 2:25 p.m. ET: All Montgomery County schools are on lockdown, WDBJ TV reports.

Update at 2:04 p.m. ET: Virginia Tech says the police officer was shot and killed after pulling someone over in what was a routine traffic stop in the school's Coliseum parking lot. Witnesses tell police that the shooter ran toward a parking lot on campus, the Associated Press reports.

A second person was found dead in that parking lot, the AP says.

Update at 1:59 p.m. ET: Virginia Tech confirms police officer, 1 other person killed in shootings on campus, the Associated Press reports.

Update at 1:55 p.m. ET: Police are investigating unconfirmed reports of shots fired at Johnson Hall.

Update at 1:52 p.m. ET: Police are clearing the Performance Arts Building, Collegiate Times reports on its Twitter account.

Update at 1:48 p.m. ET: Police are responding to unconfirmed reports of shot from Torgersen Hall. Collegiate Times, the university newspaper, also says that students have reported shots from the building.

Update at 1:28 p.m. ET: The Associated Press reports that a law enforcement official, who spoke on condition of anonymity, said initial reports indicate that the shooting occurred following a traffic stop.

Update at 1:25 p.m. ET: Police say the suspect is carrying a pistol or a "long gun."

Update at 1:23 p.m. ET: Social media immediately lit up with posts about the report of shots fired on the Virginia Tech campus.

"VaTech is on lockdown," wrote one poster on Twitter. "Hoping we don't have repeat of the past. What part of no guns at school is apparently hard to get."

Update at 1:18 p.m. ET: Virginia Tech reports that a police officer has been shot on campus and there may also be a second victim. The shootings are reported in the Coliseum parking lot. "Stay inside. Secure doors. Emergency people are responding," the university website tells students.

Update at 1:02 p.m. ET: The university says shots were reported near a campus parking lot and tells students to stay inside.

Update at 12:48 p.m. ET: The Virginia Tech website says the shooting suspect is described as a white male, with gray sweat pants, gray hat, with neon green brim, maroon hoodie and backpack. The report says the suspect is on foot walking toward the McComas building.

The university, located in Blacksburg, Va., has issued a security alert and asked students with information to call 911.

On April 16, 2007, a student, Seung Hui Cho, went on a shooting rampage that left 33 dead, including himself. An administrative hearing began on Wednesday in Washington on whether the school should pay $55,000 in fines in connection with the shootings.