A pupil reportedly armed with a crossbow has allegedly killed a teacher and injured at least three others at a high school in Barcelona.

A police spokesman said the 13-year-old has been detained on suspicion of murder on Monday morning - and there are unconfirmed reports a crossbow was used.

According to local media, the teenage boy had arrived in class an hour late, and had a crossbow and a knife in his backpack.

He is suspected of targeting a female teacher and her daughter first.

Both are believed to have suffered non-serious wounds, although the woman reportedly sustained injuries near her eyes and face.

A male substitute teacher who then entered the classroom to stop the attack is believed to have been fatally stabbed in the chest with "a bladed weapon". He had only been working at the school for a few weeks, El Diario reported.

The third person to be injured was another pupil, who was stabbed with a knife.

A 14-year-old student has been taken to Sant Pau hospital with a chest wound.

Xavier Trias, the mayor of Barcelona, has said he is "appalled" by the "tragic attack".

The incident took place at around 9:20am local time (8:20am Irish time) this morning, at the Joan Fuster Institute in La Sagrera.