New Delhi, April 6 : A 16-year-old girl was allegedly raped by an intruder who had entered an under-construction building in Delhi's Ashok Vihar area with the intention of robbery, a police official said on Thursday, adding that the perpetrator has been arrested. According to the police, the girl's parents, who worked as labourers at the building, were not present at the time of the incident which occurred on Tuesday. They had gone to collect their wages. Taking advantage of their absence, the accused entered the under-construction building to loot valuables. "The intruder then saw the victim and her 18-year-old sister alone and threatened them with a knife. He then took the victim to a secluded spot in the building where he allegedly raped her," the official said. A case has been registered and further probe is underway. /IANS