Gunmen have taken several dozen people hostage at an international school in north-western Cambodia, police say.
Six men stormed the school in Siem Reap, and are holding children aged between two and six, from countries including the UK, the US and in Asia.
The hostage-takers are said to have demanded $1,000, weapons and a car with which to escape.
A police official told Reuters news agency they were negotiating with the men, but had not reached a solution.
Attackers armed with shotguns are said to have stormed the private school at about 0930 (0230 GMT).
They seized two kindergarten classes and a number of teachers.
A witness told Reuters the captives come from Japan and several other Asian countries, Australia, the US and across Europe.
One British child is also being held.
Reports from the scene say the men demanded cash, six AK-47 assault rifles, six shotguns, hand grenades and a car.
A government spokesman said up to 70 hostages had originally been detained, but the gunmen set free one of the classes later in the morning.
"Military police in Siem Reap have surrounded the school, but the group is hiding behind the students and teachers," deputy military commander Cheang Sokhon in neighbouring Kampong Thom province told AFP.
Police and the hostage takers are said to be negotiating by mobile phone.
The motive for the seizure is still unclear.
The school is near Cambodia's most famous tourist attraction
Correspondents say the school is used mainly by foreign residents in the gateway town for Cambodia's most popular tourist attraction, the Temples of Angkor.
The relative prosperity of the area is in marked contrast to the rest of Cambodia, which is one of the poorest countries in South East Asia.
The hostage-takers have yet to reveal whether they are members of any organisation.
Acts of terrorism are extremely unusual in Cambodia, the BBC's Guy Delauney reports from the capital, Phnom Penh.
The leader of the outlawed Cambodian Freedom Fighters was recently arrested in the US on terrorism charges.