At least 33 people are dead and 29 more injured after a gunman opened fire Monday morning at Virginia Tech residence hall and classroom building in the worst mass shooting in US history, police said.

According to police, the carnage started at 7:15 am when two students were shot in the west Ambler-Johnston residence hall. About two hours later, gunshots erupted at Norris hall, where most of the 32 victims were killed. The gunman’s body was also found there, an apparent suicide.

Police identified the shooter as 23 year old Cho Seung-Hui, an English major from South Korea.

Four of the victims have been identified as of Tuesday morning: G.V. Loganathan, a professor of civil and environmental engineering and Liviu Librescu, a professor of engineering science and mechanics, Ross Alameddine, a student from Saugus, Massachusetts, and Matthew La Porte, a student from Dumont, New Jersey.

“Today the university was struck with a tragedy that we consider of monumental proportions,” Virginia Tech President Charles Steger said. “The university is shocked and indeed horrified.”

No motive has been given, though student Erin Sheehan, who was in a German class in Norris hall at the time said she saw the shooter looking for somebody.

“He peaked in twice, earlier in the lesson, like he was looking for someone, before he started shooting,” she told the Collegiate Times, one of Virginia Tech’s student newspapers.

After hearing “something like drilling in the walls,” Sheehan and her classmates tried to barricade the door “to stop anyone from coming in.” It didn’t work.

“I saw bullets hit people’s body,” she said. “There was blood everywhere. People in the class were passed out, I don’t know maybe from shock from the pain.”

Sheehan was one of four students to make it out of the room alive. “The rest were dead or injured,” she said.

Police are investigating claims that the shooter was looking for his ex-girlfriend.

University officials are receiving criticism for delaying notification of the student body regarding the shootings.

An email was sent out at just before 9:30, more than two hours after the first shots at west Ambler-Johnston hall. It said simply, “A shooting incident occurred at West Amber Johnston earlier this morning. Police are on the scene and are investigating.”

“What happened today, this was ridiculous,” student Jason Piatt told CNN. “While they’re sending out that e-mail, 22 more people got killed,” he added.

“I think the university has blood on their hands because of their lack of action after the first incident,” freshman Billy Bason told the AP.

Officials defended their decision saying they had “reason to believe” that the gunman had left campus after the initial attack.

“We had no reason to suspect any other incident was going to occur, Steger said. “We can only make decisions based on the information you had at the time.”

“You don’t have hours to reflect on it,” he added.

The shooting brought forth immediate calls for sympathy and support from college campuses across the country.

Candlelight vigils and memorial services are being planned at the George Washington and Georgetown universities. The University of Maryland will have a moment of silence at noon on Tuesday. The social networking site Facebook currently has over 300 groups dedicated to commemorating the massacre.

Indeed, technology played an important role as the events unfolded. CNN aired a 41 second clip shot by Virginia Tech student Jamal Albarghouti of the police approaching a stone building as several shots were fired. Photos uploaded to CNN’s website were posted online.

One Facebook group, called “I’m ok at VT” became a forum where students could come and ask for information about friends and loved ones.

“Does anyone know the status of Mike Pohle? His parent cannot get in touch with him and are EXTREMELY concerned. Please reply! Please please please!” reads one post.

Other posts gave updated information on victims, including a list of students who were still unaccounted for.

Monday’s shooting was the worst mass shooting in American history. In Killeen, Texas in 1991 George Hennard shot 23 people in a cafeteria before killing himself.

The massacre brought back memories of the Columbine High School shooting in Littleton, Colorado, when students Dylan Klebold and Eric Harris killed 12 students and a teacher before committing suicide.

The last mass shooting at a university occurred in at the University of Texas in Austin, when Charles Whitman shot 16 people with a rifle from the observation deck on the clock tower before being shot by police.