A woman drugged her landlord's family in Daniawan and fled with their gold jewellery and other valuables late on Saturday night.

The victims have been admitted to the intensive care unit in a nursing home.

Police said businessman Ganauri Singh (50) and his wife, Mina Devi (45), had rented out their one-room flat to a middle-aged woman about a week ago. The woman had told the trader's family that her children would join her later this month. As she was alone, she used to share meal with the couple, who own a grocery shop at Daniawan Bazaar, on the outskirts of the city.

On Saturday evening, the tenant, in her forties, cooked the dinner and served it to the Singh family. Thereafter, they went to sleep. When Ganauri woke up in the morning, he felt dizzy and collapsed. His neighbours found that not only Ganauri but also his wife Mina and children Priyanka (20) and Raviranjan (15) were lying unconscious.

The tenant was, however, absconding. The neighbours admitted the victims to a Daniawan-based hospital from where they were later referred to Patna Medical College and Hospital. They were later shifted to a private nursing home.

Daniawan police station house officer (SHO) Vibha Kumari said the members of the Singh family were shifted to a private nursing home in the capital after their condition deteriorated. "None of the family members is in a condition to talk. Police are in the dark about the identity of the tenant, who escaped with ornaments and other valuables after the incident," she said.

Sub-inspector Arun Kumar Pandey, investigating the case, said the family had not approached the police for verification of the tenant's antecedents.

Pandey said the suspect's room was searched but nothing was found that could help establish her identity. "We hope to get clues in the case after the victims gain consciousness," said the investigating officer. A neighbour, who admitted all the four members of the Singh family to the hospital, said the suspect was spotted at the couple's grocery shop around a week ago.

"Prima facie, the woman appeared to be associated with a professional gang of robbers," the officer added.

The police have started hunting for one Pappu, the owner of a cellphone shop, who had allegedly introduced the woman to the family. Police gained this information from one of the neighbours of the victims.