A gunman killed five girls and wounded seven before shooting himself in an Amish school in the US state of Pennsylvania.
The rural school is used by children aged up to 13 years
Monday's attack by 32-year-old truck driver Charles Carl Roberts took place in a one-room school in the village of Paradise near Nickel Mines in Lancaster County.
Pennsylvania state police commissioner Jeffrey Miller explained how events unfolded.
Roberts entered Georgetown School in Paradise and began addressing the pupils, showing them an automatic handgun. He was also armed with a shotgun.
In the classroom were 15 male pupils, 10-12 female pupils, one teacher and a number of assistants - older children and adults.
He told the boys to leave, along with a pregnant woman and three others with infants.
The teacher also managed to leave the classroom and called the police at 1036 local time (1436 GMT).
The gunman made the girls line up in front of the blackboard, where he tied their feet using wire or plastic cuffs.
He then barricaded the doors with large pieces of wood he had brought with him.
State troopers arrived at the scene at about 1045 and set up a cordon around the school.
The officers tried hailing the gunman on their car loudspeakers, but were unable to make contact.
At this time an emergency operator in Harrisburg, Pennsylvania, received a call from someone who said they had been called by the gunman.
The gunman reportedly warned that if the police did not immediately pull back from the area he would open fire on the hostages.
This message was relayed to the officers at the scene, but they heard shots fired in rapid succession as it was going through.
Police stormed the building, breaking the windows to enter.
They found the gunman dead, along with the bodies of three girls.
"One of the children died in the arms of one of our troopers," Mr Miller said.
Eight girls were found injured, at least three of whom were shot in the head. One of them later died in hospital.
Mr Miller said the victims had been shot one by one, "execution style".
'Not coming home'
The gunman was a local milk tanker driver who often picked up milk from Amish farms in the area.
A father of three, he had worked his night shift as usual on Sunday night, finishing at 0300 on Monday.
His wife said he had seemed perfectly normal as he walked his children to the school bus at 0845, as he did every day.
However, when his wife returned to the family home around mid-morning she discovered suicide notes that he had written to each of his children.
At 1100 she received a call from Roberts in which he said he was "not coming home" and that the police were with him, just prior to the shootings.
The authorities are examining suicide notes and believe Roberts' actions came in revenge for an event 20 years ago. They have given no further details.
They are also looking at whether the death of an infant daughter in 1997 may have played a role in the attack.