A teacher at a school in the Spanish city of Barcelona has been killed by a pupil armed with a home-made crossbow and a knife.
The suspect, reportedly a 13-year-old boy, has been arrested but may not face charges because of his age.
The teacher killed was protecting a colleague during the incident at the Instituto Joan Fuster, reports say.
Four other people were wounded. Police have not confirmed the weapon used and there is no indication of his motive.
The boy was said to have arrived late for a class on Monday morning and wounded a Spanish language teacher and her daughter, who was also a student.
Hearing screams, a male teacher covering as a substitute for a colleague entered the classroom and was fatally wounded when the boy attacked him.
A police spokesman could not confirm whether he had been fatally wounded by the boy's knife or his makeshift crossbow.
The man had only begun working at the school in recent weeks.
Students at the school said the crossbow had been fashioned out of wood and ballpoint pens and that the boy had thrown it into a rubbish bin before running off.
According to Spanish media, the pupil had spoken of killing all his teachers last week, and had a list of 25 names, but his schoolmates had dismissed his comments as a joke.
Spain's ANPE teachers union says it is the first documented case of a pupil killing a teacher in the country.
If the attacker is confirmed as a 13-year-old, he would not face charges as the age of criminal responsibility in Spain is 14.
The Mayor of Barcelona, Xavier Trias, tweeted that he was appalled by the incident and has pledged his support for those affected.
The four people wounded in the attack, two teachers and two teenagers, were not badly hurt.