BARCELONA, Spain » A 13-year-old Spanish boy armed with a crossbow and a machete killed a substitute teacher and wounded four other people at his school in Barcelona on Monday, police said.

The unidentified boy was detained by police as a suspect in the attack that also saw two other teachers and two students injured. Authorities said the boy, who was undergoing a psychiatric examination, will not face criminal charges because he is under the age of 14.

The attack, which took place just after 9.30 a.m., sowed terror in the high school in a working class neighborhood of Spain’s second-largest city.

"We were just starting the class and suddenly we heard screams," said student Gemma Jarque. "So we shut ourselves inside our classroom in order to be safe."

A regional police spokeswoman said the boy had a crossbow and a machete. However, she was unable to say which weapon caused the man’s death. She spoke on condition of anonymity because of police regulations that prevent her from being identified by name.

An autopsy was being performed to determine the teacher’s cause of death. Results are not expected for several days.

Authorities did not disclose details of how the attack played out. But Jarque said she and others hid in her classroom after hearing the screams, and left along with other students only after a fire alarm sounded.

"We saw the teacher lying on the floor in a pool of blood," she said.

Another student, Paula Amayuelas, said she knew the suspect, who police did not identify because of his age. Amayuelas said the boy "didn’t have problems but he was kind of a loner …. Other students would pick on him."

The two wounded students and one of the injured teachers were taken to Barcelona hospitals for treatment while the other injured teacher was treated at the scene and did not need hospitalization.

Parents and students gathered and hugged each other in stunned silence outside the school for students ages 12-16. The teacher killed was a substitute who had worked at the school for about a week, students said.

Though children below 14 are not held legally responsible for crimes and cannot be jailed or placed in juvenile detention centers, they can be sent to mental health institutions, said a spokesman for Spain’s Justice Ministry who spoke on condition of anonymity because of ministry policy.

Following his detention, the boy was taken to a hospital for a psychiatric examination, said Jose Miguel Company, a spokesman for the Barcelona prosecutor’s office.

"He was very disturbed and saying strange and incoherent things," said Company, who added that the examination is aimed at determining whether the boy has psychiatric problems or whether he was faking them.

School attacks are extremely rare in Spain. A national police spokesman could not recall any fatal school attacks in the country’s recent history.

Spain did avert an attempt in 2012 by a 21-year-old Spanish man who allegedly wanted to imitate the attack at Columbine High School in Colorado that killed 12 students and one teacher.

A spokesman for regional police said it was too early to determine whether Monday’s attack was an attempt to copy the Columbine attack, which took place 16 years ago to the day.

Giles reported from Madrid. Alan Clendenning and Jorge Sainz in Madrid contributed to this report.