A gang of three allegedly raided a ground-floor flat in Jodhpur Garden, gagged a 78-year-old widow living alone and robbed cash and jewellery by holding her at gunpoint on Monday afternoon.

Bimla Gupta, the widow, told police that she had been gagged so hard that one of her teeth came off.

The apartment block is in a blind lane, barely 100m from Prince Anwar Shah Road and near South City Mall.

The area has a large number of standalone residential buildings and two police stations - Lake and Jadavpur - are in the vicinity.

"The three, who the lady said looked like teenagers, struck around 12.30pm. They spent around 20 minutes in the flat and fled towards Prince Anwar Shah Road," said an officer of Lake police station.

Policemen are posted in front of South City Mall but they had no clue about the incident.

Gupta's statement to the police said the doorbell of her flat had rung around 12.30pm. She looked through the eye-hole but could see no one.

She has four grandsons and one granddaughter from her three children. Three of her grandsons (from her two sons) live in Calcutta and visit her occasionally. The woman told the police that she opened the door thinking one of her grandsons had come to visit her.

"As soon as I opened the door, three persons overpowered me and entered my flat. Two of them attacked me with their hands while the third took out a firearm. They threatened me not to shout," Gupta stated in her complaint.

Scared, she complied with the trio's instructions.

"They took the keys of my almirah and rummaged through the articles," she mentioned in her statement. "They took away Rs 20,000 and gold and silver jewellery weighing around 70g. When they wanted to take away my bangle, I said it was made of bronze. They did not take it. The bangle was a gift from my husband."

Before leaving the apartment, one of the robbers apparently called up someone and asked that person to keep "the car ready".

Gupta alerted the neighbours after the trio had left.

"The robbery has left everyone in the area scared. It's shocking that such an incident could take place around 12.30pm," Minati Roy, a neighbour of Gupta, said.

Gupta had hired a domestic help named Bhagabati six months ago. "Bhagabati is from Dakshin Barasat in South 24-Parganas and works in other houses in the area, too. She had left Gupta's flat around noon, half an hour before the robbers came. We are questioning her," an officer of the detective department said.

Gupta has been living in the 600sq ft flat alone since the death of husband Madan Mohan Gupta, who had retired from a public sector undertaking, in 2013.

Her elder son Ajay, 54, who runs a business of manufacturing electrical parts in Behala, lives with his family in an apartment in Jodhpur Park. The other son, Bijoy, 52, works in a private firm and lives with his family in Mahamayatala, near Garia. Gupta's only daughter, Aruna Dangaic, 50, lives in Siliguri.

Last month, an elderly couple were murdered in their Paikpara apartment by a man they had known for long and trusted.