Shyam Thapa, a Class IV student, was injured in the head after being hit by a brick that fell from the top floor of a five-storeyed building under construction in Swinhoe Lane, Kasba, on Monday.

The nine-year-old boy has been admitted to Ruby General Hospital, where he underwent a surgery. He will be kept under observation for the next 24 hours.

Anath Pal, the promoter of the building, has been arrested. The superintendent of South 24-Parganas police, Ajey Ranade, said Pal had been arrested for failing to take safety measures while constructing the building in a residential area.

“Work has not been stopped. Pal’s men have been asked to take all precautions,” said Kumar.

Shyam was returning home from school with his grandmother when a few bricks fell from the top floor of the structure around 10.45am. One of the bricks hit Shyam on the head.

Residents took Shyam to the hospital. “The boy’s injury was critical. He vomited twice. He is not out of danger yet,” said S.B. Purkayastha, the chief executive officer of the hospital.

Pujan Purakait, an uncle of Shyam, said the masons, who have been working there for quite some time, did not take any safety measures despite repeated pleas from the residents.

Shyam’s father Rajesh works in a travel agency in Jodhpur Park.

Lalbazar fire: A fire broke out in the detective department office at the Lalbazar police headquarters on Monday evening. Policemen put out the fire before firemen reached the spot. A short circuit sparked the blaze.