Chea Khom quit last week as a driver for a Korean restaurant owner in Siem Reap, gateway to the famed 800-year-old temples, after being slapped in the face for taking the children to school late, senior police investigator Ou Em said on Friday.

He then decided to exact revenge by kidnapping the Korean's children from the school, hatching a plot with friends in Phnom Penh which led ultimately to Thursday's school siege and the death of a two-year-old Canadian boy, he said.

Plan gone awry

"When he entered the school, his first target was to kidnap the Korean children, but when he saw the parents of the children, he was afraid to do it," Ou Em said. "So he turned to another classroom and took them hostage."

"The gunmen demanded we give them money, a van and grenades. We did not agree ... so they got mad and shot the kid in the head"

Police negotiator

Armed with knives and a handgun, the four hostage-takers, all in their 20s, first demanded $1000 and a van in return for the release of the 29 infants in the class. Later, they increased the sum to $30,000, police said.

When negotiators stalled over the demand for weapons, Chea Khom and his accomplices started to lose their cool.

"The gunmen demanded we give them money, a van and grenades. We did not agree to give them grenades and guns, so they got mad and shot the kid in the head," he said.

Toddler killed

Kanika Cowled, a six-year-old Cambodian-Australian girl who hid in the school library, said the Canadian child was singled out and shot "because that little boy just yell".

The children were rescued after 
their eight hour ordeal

After an eight-hour stand-off, police and soldiers armed with AK-47 assault rifles stormed the school compound as the kidnappers tried to make their escape with several of the children in a 12-seater van.

Ou Em said the four, who were paraded battered and bruised before reporters at Siem Reap police station, 200km  northwest of the capital, would be sent to court on Saturday morning to be charged with robbery and kidnap.

Police said they had arrested a fifth man, a 29-year-old souvenir shop security guard who is alleged to have acted as the plot's mastermind, although he did not take part in the attack.

Distraught parents

An eerie calm had settled on Friday on the dirt road leading to the school, which had been packed the previous day with soldiers and police, as well as distraught parents and onlookers.

About 20 military policemen stood guard in front of the school and police said security had been stepped up at all tourist locations to ensure the safety of visitors.

"This incident has forced us to improve security, not only at hotels but also guest houses and restaurants where foreigners are," said provincial police chief Noun Bophal.

"This is a lesson for us."

Child trauma unit

Doctors at the town's main hospital were setting up a trauma unit for the children, who came from as many as 14 different countries, to help them overcome the ordeal.

Several policemen were injured
when ending the stand-off

"Some of these children will be traumatised for a long time," said Georges Dallemagne of Siem Reap Hospital. "It's important that this be set up as soon as possible so the children can talk about their experience and say what they feel."

The violence left the hundreds of expatriates in the sleepy town in shock and raised a question mark over the future of the tourism industry in the southeast Asian nation, which is still recovering from the Khmer Rouge genocide of the 1970s.

"Siem Reap is a lovely place. Everyone here is shocked and horrified because you don't expect something like this to happen here," said Briton Karl Balch, who has lived in Siem Reap for six years, running the Ivy Bar and Guesthouse.

"The expat community is going to be severely affected by this, but to Khmers, it's just another day," said David Cowled, an aid agency worker.