By Charles Scanlon
BBC News, Seoul
Cho Seung-hui's childhood home in South Korea is a small, dilapidated apartment in a low income neighbourhood on the fringes of Seoul.
He and his family lived in the now-vacant apartment 15 years ago, before emigrating to the US.
Cho Seung-Hui lived in a basement flat in this apartment block in Seoul
The family's landlady said the father had complained that life was too hard in Korea. He wanted to go to the US because he didn't know anyone there, she said, and he wanted a fresh start in a new country.
"When I first heard a Korean did the shooting I got the shivers," said an old woman and former neighbour of Cho's family, who refused to be named.
"I was so shocked and upset. I remember those two children running around here. It's hard to believe it ended this way."
Cho Seung-hui was only eight when he left this house with his sister and parents.
He attended a nearby primary school, whose only record of him is an entry saying he emigrated in January 1992.
It was the tail-end of a wave of Korean migrants who crossed the Pacific looking for a better life.
The family seems to have had very little contact with Korea since, but that has not stopped an extraordinary public reaction.
People are shocked and ashamed and some worry the incident will have a damaging impact on the nation.
Worries of backlash
Across town at the US embassy, the flag is flying at half mast. Some Koreans worry that relations could be damaged, and that Korean communities in the US could be targeted.
People gathered in the centre of Seoul for a candlelit vigil to show their sympathy for the victims and their families.
They were also here to apologise - there's a remarkable mood of collective shame for the actions of a lone gunman who just happened to be born in this city.
After all, there was a huge reaction a few years ago, when an American military vehicle ran over two Korean school girls and killed them in an accident. Hundreds of thousands came out onto the street to protest against the US, and a very anti-American sentiment developed.
People here are concerned that they may see a mirror image of that happening in the US, however unlikely that may sound to outsiders.
This sentiment is reflected in an article in the Korea Herald which expressed concern over how the nation should minimize tension.
"It would be a good idea to send a delegation to Virginia Tech to express the condolences of the nation," it said.
Korean President Roh Moo-hyun said in a news conference that he couldn't express the level of his shock. "We feel a deep bitterness," he said.
"I want to deliver my sincere words of consolation to the families of the killed and injured and all US people. I wish US society would quickly overcome its sorrow and regain calmness."
Mr Roh also sent a telegram of condolence to President George W Bush, and his government has put consulates in the US on alert.
There are worries about a backlash, with two million ethnic Koreans in the US, even though the incident comes at a time of successful relations between the two countries.
Most recently, Korea and the US have concluded negotiations on a bilateral free trade agreement.