Two men wearing orange jackets and posing as civic employees allegedly entered a flat at a guarded housing complex in Madurdaha and gagged an elderly woman before robbing gold ornaments and cash on Monday afternoon.

Minakshi Sarkar, 72, was alone in her second-floor flat in Sunflower Block of Deeshari Housing complex, off Madurdaha Main Road, when the calling bell rang.

She opened the door and found two men in orange jackets, introducing themselves as employees of the water supply department of the Calcutta Municipal Corporation. The men were wearing the type of jackets usually worn by ground-level civic staff.

Police said Sarkar was initially reluctant to let the men in but finally did so after they said they wanted to check the water lines in the house.

Later, when it occurred to her that she had not lodged any complaint related to water supply, she tried to contact guards of the complex over the intercom.

But before she could do so, the police said, the men allegedly locked the door from inside and overpowered her.

“She was incapacitated and gagged with a pillow cover. The robbers demanded Rs 5 lakh. She said she did not have the money, after which the robbers started ransacking the cupboards,” said a senior police officer.

Sources said one of the robbers headed straight to a place in the room where clothes were stacked up and fished out the key to the family locker from under the clothes.

The family lodged a police complaint stating that Rs 6,000 and gold jewellery had been robbed from the house.

“It was apparent the men had specific information about where the locker key had been kept,” the officer added.

The robbers fled leaving the flat door open. A member of the housekeeping staff of the housing complex found a gagged Sarkar inside and alerted guards at the gates. The accused had by then most likely left the complex.

The police have learnt that the accused had entered the building through the back gate and left through the front.

“We have got hold of CCTV footage that shows the faces of the two accused wearing orange jackets,” an officer said.

The police said Sarkar and husband Satya Bikash Sarkar live in the apartment. The couple’s son lives with his family in another apartment on the same floor.

The housing complex, a few hundred metres from the EM Bypass, has 32 blocks and is guarded by security personnel and is under CCTV surveillance. The entrance has a boom barrier to regulate access.

“This was not the first time CMC men visited the building. They enter through the back gate. Today was no exception. The guards are saying they had not spotted anything suspicious,” the officer said.

CMC officials told Metro no personnel of the water supply department would visit a house to check the water pipes unless there is a complaint. “The safest way to verify a person’s identity is to check his or her identity card. But ground-level contractual workers of the CMC are not issued any I-card,” an official said.