Police have also recovered the stolen items that included a two watches, a diamond ring, a mobile phone and about Rs 50,000 in cash from the alleged robbers, all residents of Bihar, he said.
The alleged culprits have been identified by the police as Mohd Yusuf (42), Hira Lal (24), Ashok (23), Sharvan (28), Arjun Kumar (21), Mahesh Shah (22) and Salman (26), most of whom used to work as labourers in a shoe factory.
But during the investigation, the servant Mahesh Kumar confessed to have conspired with his accomplices in committing the robbery, police said.
"The servant had passed on the information about the presence of valuables in the house to his friends following which they hatched a robbery plan. He had kept the main gates of the house open to let the others enter," said police.