A pupil has been arrested after allegedly shooting dead his classmate during an IT lesson at a school in Thailand today.

The suspect allegedly blasted Noppasin Ngamsud, 14, in the head as he sat at the Acer desktop PC in a classroom in Nonthaburi on the outskirts of Bangkok shortly before 1:30 pm local time.

Horrified classmates said they thought a 'computer had exploded' when they heard the blast. They saw Noppasin collapsed on the floor with blood pouring from a wound on his head.

Paramedics rushed to the scene and bandaged the schoolboy's skull before performing CPR but he was pronounced dead at the scene. They said he had a wound that was 'three or four centimetres long exposing his skull'.

Officers reportedly arrested a classmate over the shooting. He was taken to the Bang Bua Thong Police Station where he has been remanded in custody.

Noppasin's devastated relatives gathered at the school and broke down in tears.

A pupil who sat next to Noppasin said: ‘My friend Noppasin had the computer on for about 10 minutes then there was a sound like it had exploded.

'I turned my head and Chok was already on the floor. I have tinnitus because the bang was so loud.'

Computer studies teacher Sasina Rakpan said: 'I was sitting in front of the room when I heard a loud bang at 1.30 PM. I raced to Noppasin and saw his blood everywhere. I immediately contacted the emergency services and asked other students to quickly tell the other teachers.'

The suspect was taken to the Bang Bua Thong Police Station where officers are questioning him as well as classmates and teachers.

Police Lieutenant Saiyon Thongtha said: 'The victim had a serious facial injury. Above the left eyebrow area, there was a deep fracture, showing the bone, about three or four centimetres long. The paramedics from the Po Tek Tung foundation rushed to pump his heart but unable to sustain his life.'