Rajarhat: A Class VIII boy cycling to school with his younger brother was killed on Wednesday when a boundary wall against which scores of marble tiles had been stacked collapsed on them at Hatiara on the fringe of New Town.

Sayan Roy, 14, was dead by the time he was found under the rubble of bricks and marble along a narrow road. His brother Ayan, 6, is at RG Kar Medical College and Hospital with multiple injuries.

The siblings were passing by the compound of Moti Marble and Tiles, close to Ayan's school, when the 12ft high wall possibly crumbled under the weight of the tiles resting on them. The average weight of marble is more than 6kg per square foot.

"The marble tiles had been unloaded from a mini truck in the morning," a resident of the area said.

As news of Sayan's death spread, a 100-strong crowd ransacked the compound and set fire to a Hyundai Santro parked there. The mini truck was also damaged in the mob fury.

Several of the protesters said a tragedy like this was waiting to happen since the allegedly illegal warehouse came up in what is otherwise a residential neighbourhood.

"Sayan was supposed to drop Ayan at his school and proceed to the Chittaranjan Colony Hindu Vidyapith in Deshbandhu Nagar, where he was a student. Their father usually escorts Ayan to school, but Sayan volunteered on Wednesday because his brother had an examination," said Anita Dey, a cousin of the brothers.

He was taken to the Bidhannagar Sub-Divisional Hospital by a police team, but was declared dead on arrival. "He had lost a lot of blood. We found a massive head injury that probably killed him," said a doctor at the hospital, around 10km from Hatiara.

Sujoy Basu, who lives close by, said he had asked the owner of Moti Marble and Tiles not to stack marble against the roadside wall and also complained to the erstwhile Rajarhat Gopalpur Municipality in writing about this unsafe practice.

"When I heard a very loud noise this morning, I feared the worst. A brick wall cannot support a stack of heavy marble slabs. Alas, the owner of the marble business did not pay heed," Basu said.

A police contingent supplemented by a Rapid Action Force team was deployed in the neighbourhood to prevent a further backlash. The crowd dispersed only after senior police officers promised corrective steps.

The police have started a case against Pushpa Naskar, the owner of Moti Marble and Tiles, for culpable homicide not amounting to murder and criminal negligence. He had fled Hatiara after the incident and was absconding till late on Wednesday.