BLACKSBURG, Va. – The gunman suspected of carrying out the Virginia Tech massacre that left 33 people dead was described Tuesday as a sullen loner whose creative writing in English class was so disturbing that he was referred to the school’s counseling service.

News reports also said that he may have been taking medication for depression, that he was becoming increasingly violent and erratic, and that he left a note in his dorm in which he railed against “rich kids,” “debauchery” and “deceitful charlatans” on campus.

Cho Seung-Hui, a 23-year-old senior majoring in English, arrived in the United States as boy from South Korea in 1992 and was raised in suburban Washington, D.C., officials said. He was living on campus in a different dorm from the one where Monday’s bloodbath began.

Police and university officials offered no clues as to exactly what set him off on the deadliest shooting rampage in modern U.S. history.

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

On Tuesday afternoon, thousands of people gathered in the basketball arena, and when it filled up, thousands more filed into the football stadium, for a memorial service for the victims. President Bush and the first lady attended.

Virginia Tech President Charles Steger received a 30-second standing ovation, despite bitter complaints from parents and students that the university should have locked down the campus immediately after the first burst of gunfire. Steger expressed hope that “we will awaken from this horrible nightmare.”

“As you draw closer to your families in the coming days, I ask you to reach out to those who ache for sons and daughters who are never coming home,” Bush said.

A vast portrait of the victims began to emerge, among them: Christopher James Bishop, 35, who taught German at Virginia Tech and helped oversee an exchange program with a German university; Ryan “Stack” Clark, a 22-year-old student from Martinez, Ga., who was in the marching band and was working toward degrees in biology and English; Emily Jane Hilscher, a 19-year-old freshman from Woodville, Va., who was majoring in animal and poultry sciences and, naturally, loved animals; and Liviu Librescu, an Israeli engineering and math lecturer who was said to have protected his students’ lives by blocking the doorway of his classroom from the approaching gunman.

Meanwhile, a chilling portrait of the gunman as a misfit began to emerge.

Professor Carolyn Rude, chairwoman of the university’s English department, said she did not know Cho. But she said she spoke with Lucinda Roy, the department’s director of creative writing, who had Cho in one of her classes and described him as “troubled.”

“There was some concern about him,” Rude said. “Sometimes, in creative writing, people reveal things and you never know if it’s creative or if they’re describing things, if they’re imagining things or just how real it might be. But we’re all alert to not ignore things like this.”

She said Cho was referred to the counseling service, but she said she did not know when, or what the outcome was. Rude refused to release any of his writings or his grades, citing privacy laws.

The Chicago Tribune reported on its Web site that he left a note in his dorm room that included a rambling list of grievances. Citing unidentified sources, the Tribune said he had recently shown troubling signs, including setting a fire in a dorm room and stalking some women.

ABC, citing law enforcement sources, reported that the note, several pages long, explains Cho’s actions and says, “You caused me to do this.”

Investigators believe Cho at some point had been taking medication for depression, the Tribune reported.

Classmates said that on the first day of an introduction to British literature class last year, the 30 or so English students went around and introduced themselves. When it was Cho’s turn, he didn’t speak.

The professor looked at the sign-in sheet and, where everyone else had written their names, Cho had written a question mark. “Is your name, `Question mark?'” classmate Julie Poole recalled the professor asking. The young man offered little response.

Cho spent much of that class sitting in the back of the room, wearing a hat and seldom participating. In a small department, Cho distinguished himself for being anonymous. “He didn’t reach out to anyone. He never talked,” Poole said.

“We just really knew him as the question mark kid,” Poole said.

The rampage consisted of two attacks, more than two hours apart _ first at a dormitory, where two people were killed, then inside a classroom building, where 31 people, including Cho, died after being locked inside, Virginia State Police said. Cho committed suicide; two handguns _ a 9 mm and a .22-caliber _ were found in the classroom building.

One law enforcement official said Cho’s backpack contained a receipt for a March purchase of a Glock 9 mm pistol. Cho held a green card, meaning he was a legal, permanent resident, federal officials said. That meant he was eligible to buy a handgun unless he had been convicted of a felony.

Roanoke Firearms owner John Markell said his shop sold the Glock and a box of practice ammo to Cho 36 days ago for $571.

“He was a nice, clean-cut college kid. We won’t sell a gun if we have any idea at all that a purchase is suspicious,” Markell said. Markell said it is not unusual for college kids to make purchases at his shop as long as they are old enough.

“To find out the gun came from my shop is just terrible,” Markell said.

Investigators stopped short of saying Cho carried out both attacks. But ballistics tests show one gun was used in both, Virginia State Police said.

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

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 the link was not yet definitive. “There’s no evidence of any accomplice at either event, but we’re exploring the possibility,” he said.

Officials said Cho graduated from Westfield High School in Chantilly, Va., in 2003. His family lived in an off-white, two-story townhouse in Centreville, Va.

Two of those killed in the shooting rampage, Reema Samaha and Erin Peterson, graduated from Westfield High in 2006, school officials said. But there was no immediate word from authorities on whether Cho knew the two young women and singled them out.

“He was very quiet, always by himself,” neighbor Abdul Shash said. Shash said Cho spent a lot of his free time playing basketball and would not respond if someone greeted him. He described the family as quiet.

South Korea expressed its condolences, and said it hoped that the tragedy would not “stir up racial prejudice or confrontation.” “We are in shock beyond description,” said Cho Byung-se, a Foreign Ministry official handling North American affairs.

Classes were canceled for the rest of the week. Norris Hall, the classroom building, will be closed for the rest of the semester.

Many students were leaving town quickly, lugging pillows, sleeping bags and backpacks down the sidewalks.

Jessie Ferguson, 19, a freshman from Arlington, left Newman Hall and headed for her car with tears streaming down her red cheeks.

“I’m still kind of shaky,” she said. “I had to pump myself up just to kind of come out of the building. I was going to come out, but it took a little bit of ‘OK, it’s going to be all right. There’s lots of cops around.'”

Although she wanted to be with friends, she wanted her family more. “I just don’t want to be on campus,” she said.

Until Monday, the deadliest shooting in modern U.S. history was in Killeen, Texas, in 1991, when George Hennard plowed his pickup truck into a Luby’s Cafeteria and shot 23 people to death, then himself.

Previously, the deadliest campus shooting in U.S. history was a rampage that took place in 1966 at the University of Texas at Austin, where Charles Whitman climbed the clock tower and opened fire with a rifle from the 28th-floor observation deck. He killed 16 people before he was shot to death by police.