BLACKSBURG Va.

A Virginia Tech senior from South Korea killed at least 30 people locked inside a classroom building in the deadliest shooting rampage in modern U.S. history, the university and police said Tuesday.

Ballistics tests also found that one of the guns used in that attack was also used in a shooting two hours earlier at a dorm that left two people dead, Virginia State Police said.

Police identified the classroom shooter as Cho Seung-Hui, 23, a senior from South Korea who was in the English department at Virginia Tech and lived in a different dorm on campus. Cho committed suicide after the attacks, and there was no indication Tuesday of any possible motive.

“He was a loner, and we’re having difficulty finding information about him,” school spokesman Larry Hincker said.

Two law enforcement officials, speaking on condition of anonymity because the information had not been announced, said Cho’s fingerprints were found on the guns used in the shootings. The serial numbers on the two weapons had been filed off, the officials said.

One law enforcement official said Cho was carrying a backpack that contained receipts for a March purchase of a Glock 9 mm pistol.

Col. Steve Flaherty, superintendent of the Virginia State Police, said it was reasonable to assume that Cho was the shooter in both attacks but that link was yet definitive.

“There’s no evidence of any accomplice at either event, but we’re exploring the possibility,” he said.

A memorial service was planned at the university later Tuesday, and President Bush planned to attend, the White House said. Gov. Tim Kaine was flying back to Virginia from Tokyo for the 2 p.m. convocation.

The first deadly attack, at a dormitory around 7:15 a.m., left two people dead. But some students said they didn’t get their first warning about a danger on campus until two hours later, in an e-mail at 9:26 a.m. By then the second attack had begun.

Two students told NBC’s “Today” show they were unaware of the dorm shooting when they walked into Norris Hall for a German class where the gunman later opened fire.