Eleven children and a teacher were wounded in Russia when a knife fight broke out at a school in Perm, a city 1,000km (620 miles) east of Moscow.

The victims were slashed when they tried to separate two teenage boys who were fighting, investigators say.

Two suspects were detained by police and the incident is being treated as attempted murder. One boy was angry about social media posts, reports say.

The teacher and a 16-year-old are in hospital with serious neck wounds.

Some of the other injured children are believed to be aged 10. Their injuries are reported to be fairly minor.

One suspect is reportedly a former pupil of the school who previously had psychiatric treatment.

The school was evacuated and children said they had seen a trail of blood on the floor as they were led out.

A video from the scene shows one of the suspects being taken from the school by police, head down and in handcuffs.