The city police rescued four children from a house at Gulberg area in the city, where a woman, reportedly their stepmother, used to torture and keep them in chains. The residents of the area informed the police, following which the officers entered the house and rescued the children locked up since days. The police also made a video of the crime scene where children can be seen fettered with chains. According to the residents of the area, the woman used to torment the children by tying them with chains and starving them for several days. The age of the children is between four to ten years, the residents informed the police. The police further said that with the help of residents of the area, the rescued children were handed over to their father. Last year, a 13-year-old boy who was kidnapped in Karachi after being lured into a meeting via Facebook was rescued by police. Police said that a criminal gang masqueraded as an online gaming friend and abducted him after arranging to meet him last week. The gang demanded a $500,000 (£330,447) ransom. Kidnapping is a tactic frequently used by militants and criminals in Pakistan. But cases involving the use of social media to lure children are rare. The gang first made contact with the boy online months ago, police are quoted as saying in local media reports.