A 12-year-old boy was killed and his 8-year-old sister was critically injured after the portion of railing of their terrace collapsed in southwest Delhi’s Dabri Extension on Sunday morning. The incident took place around 11.30am, police said. A fire tender along with the rescue team reached the incident spot around 11.45 am. Deputy commissioner of police (Southwest) Devender Arya said the two children — Rohit and his sister Rita — were playing on the terrace when a portion of the railing came crashing down. The two children were trapped under the debris. The injured children were rescued by the fire department and police officials with the help of locals. They were rushed to Deen Dayal Upadhyay hospital where Rohit was declared brought dead.“Rita has suffered multiple fractures to her limbs. She is undergoing treatment at the hospital,” said a police officer, adding that the two children, their elder sister and parents, who work as labourers, were living in one of the five rented rooms of the single-storey house for the last eight years. Karan Brar, a local resident, said the family originally belongs to Uttar Pradesh. Brar alleged that railing of the terrace was rickety and had become weak because of rains.