Virginia Secretary of Public Safety John Marshall defended Monday's public safety response at Virginia Tech, which has been widely questioned because of a two-hour gap between shooting incidents in the West Ambler Johnston residence hall and the Norris engineering building on the other side of campus.

Marshall said Tech's president, Charles Steger, and its police chief, Wendell Flinchum, "made the right decision based on the best information that they had available at the time."

At a morning press conference, authorities also said the number of victims remained unchanged, 32 dead, 15 wounded, the worst mass shooting in U.S. history. The shooter at Norris Hall was identified as Cho Seung-Hui, 23, a senior majoring in English who also killed himself.

State Police Col. Steven Flaherty said one of the handguns recovered in Norris Hall was also discharged at West Ambler Johnston, but authorities did not confirm Cho as shooter in both crimes. Cho is a South Korean native with a resident alien permit and authorities listed his surname first in keeping with Korean custom.

All the dead were taken to the medical examiner's office in Roanoke. Authorities do not plan to identify victims until all 32 have been identified and their families notified, but multiple names have already been reported, many on the Web site of Tech's student paper, www.collegetimes.com.

Marcella Fierro, Virginia's chief medical examiner, said identification is "a process that cannot take place in haste, so this will take several days."

Tech spokesman Larry Hincker said he would talk with authorities about the possibility of confirming some victims' names sooner. He also said he was outvoted as to authorities' refusal to field questions from reporters at the morning press conference and hoped back-and-forth would be arranged later. Another briefing is expected at 5 p.m.

Steger, Tech's president, said classes are canceled for the week "to allow students the time they need to grieve and seek assistance as needed."

The university will reopen administratively Wednesday. Norris Hall will be closed for the rest of the semester, which ends next month.

Steger said counseling and other resources are available for students at McComas Hall, for employees at the Brush Mountain Room in Squires Student Center.

Flaherty, of the state police, said the crime scene in Norris was both horrific and chaotic, complicating the investigation with possessions and identifying materials strewn about.

"What went on during that incident certainly caused tremendous chaos and panic," he said, adding that victims were found in at least four classrooms and a stairwell.

"We know there were a number of heroic events that took place, by students and faculty alike," he said, without giving specifics.

He said ballistics made it "reasonable to assume" Cho was also the shooter at West Ambler Johnston but "the evidence has not led us to where we can say with all certainty that the same shooter was involved in both instances."

He said authorities had no evidence of an accomplice but had not ruled it out.