(CNN) -- The gunman who killed 30 people at Virginia Tech's Norris Hall before turning the gun on himself was student Cho Seung-hui, university police Chief Wendell Flinchum said Tuesday.
University officials said they were still trying to determine if Cho was responsible for an earlier shooting at a dormitory that left two dead.
However, Flinchum said ballistics tests show that one of the two guns recovered at Norris Hall was used at Norris and at the dorm. (Watch police disclose new information about the shooter Video)
Cho, a 23-year-old South Korean and resident alien, lived at the university's Harper Hall, Flinchum said. He was an English major, the chief said.
Cho was a loner and authorities are having a hard time finding information about him, said Harry Hincker, associate vice president for university relations.
The university and police are still in the process of releasing the names of the 32 people killed in Monday's shootings. (Watch how some are asking why warnings weren't issued sooner Video)
"What went on during that incident certainly caused tremendous chaos and panic in Norris Hall," Col. Steven Flaherty of the Virginia State Police said, describing how victims were found in four classrooms and in the stairwell of the school's engineering science and mechanics building.
A doctor at a Blacksburg hospital described the injuries he saw Monday as "amazing" and the shooter as "brutal."
"There wasn't a shooting victim that didn't have less than three bullet wounds in them," said Dr. Joseph Cacioppo of Montgomery Regional Hospital.
Even among the less serious injuries, Cacioppo said, "we saw one patient that had a bullet wound to the wrist, one to the elbow and one to the thigh. We had another one with a bullet wound to the abdomen, one to the chest and one to the head."
A source familiar with the investigation said the weapons found at Norris were a Walther .22-caliber semi-automatic and a 9 mm Glock -- both with the serial numbers filed off. (Watch how quickly these guns can be fired, reloaded Video)
Details surface
The day's first shooting, at the West Ambler Johnston dormitory, which houses 895 students, occurred about 7:15 a.m.
At the time of the later shootings at Norris Hall, police were investigating a "person of interest" in the dormitory shootings, Flinchum said Monday.
During the Tuesday news conference, Flinchum said the person of interest was an acquaintance of a woman killed at the dorm.
Flaherty said authorities were still investigating whether Cho had any accomplices in planning or executing Monday's rampage.
Steger told reporters Monday that police found the front doors of Norris Hall chained shut and that by the time they got to the second floor, the gunfire stopped.
Authorities say they believed the dorm shooting was an "isolated incident" and were still investigating it when the slaughter occurred at the other campus building, Norris Hall. (Officials thought shooter had fled)
The gunman killed 31 people, including himself, and wounded 15 in Norris Hall classrooms.
Steger: Police thought dorm shooting was isolated
Steger on Tuesday defended the university response to the dorm shooting, saying police believed it to be "a domestic fight, perhaps a murder-suicide" that was contained to one dorm room. (Watch the police chief explain where bodies were found Video)
Police cordoned off the dorm and all residents were told about the shooting as police looked for witnesses, Steger said.
"I don't think anyone could have predicted that another event was going to take place two hours later," Steger said, adding that it would've been difficult to warn every student because most were off campus at the time. (Watch a student's recording of police responding to loud bangs Video)
The gunman was dressed "almost like a Boy Scout" and wore a black ammunition vest, said a student who survived by pretending to lie dead on a classroom floor.
"He just stepped within five feet of the door and just started firing," said Erin Sheehan. "He seemed very thorough about it, getting almost everyone down, I pretended to be dead." (Watch student describe surviving by playing dead Video)
The shooter, who remained quiet throughout the rampage, came back 30 seconds after the first round of gunfire and Sheehan and her classmates tried to barricade the door with their bodies, she said.
After the shooter couldn't get in, he began firing through the door, Sheehan said. Of the 25 students in her German class, Sheehan was one of four able to walk out on her own when police arrived. (Watch students react to shooting Video)
Victims' identities being released
Courtney Dalton, an 18-year-old student who worked at West End Dining Hall, said a friend named Ryan Clark was one of the two dormitory victims.
Clark, a resident assistant at West Ambler Johnston Hall, had once worked at the cafeteria serving pizza. Sobbing, she described Clark "a happy person."
As of early Tuesday, the identities of four other victims had been released: professor G.V. Loganathan, professor Liviu Librescu, student Ross Alameddine of Saugus, Massachusetts, and student Matthew La Porte of Dumont, New Jersey. (Full story)
The university has scheduled a convocation for 2 p.m. ET Tuesday. President Bush is scheduled to attend.
Classes have been canceled for the rest of the week, and Norris Hall will be closed for the remainder of the semester, Steger said.
There have been two bomb threats at the university this month, the latest of which came Friday. Flinchum said Tuesday they were unrelated to the shootings. (Watch gunfire on the campus Video)
Last August, the first day of class was cut short at Virginia Tech by a manhunt for an escaped prisoner accused of killing a Blacksburg hospital security guard and a sheriff's deputy.
Before Monday, the deadliest mass shooting in the United States occurred in 1991, when George Hennard drove a pickup truck into a Killeen, Texas, cafeteria and fatally shot 23 people, before shooting and killing himself.
