According to Vaibhav Jain, the shop owner's son, the men arrived on two motorcycles and entered the shop around 12 PM.
Two of them were carrying country-made pistols and the others had meat-chopping knives, he said.
Mr Jain's father was sitting in the shop with a worker when the assailants entered and asked him to hand over the jewellery kept in the shop, the police said.
"They threatened us and abused us and decamped with jewellery items they could lay their hands on," Mr Vaibhav added.
Mr Vaibhav said that one of the men with a pistol in his hand told his father to stay quiet or he'd be shot dead.
"The one with a pistol threatened to shoot my father and other one with a knife came near the counter and put it near his throat and asked him to give them everything without a word," he said.
The accused had come with white empty sacks, then allegedly put the gold and diamond jewellery in them and fled. "All this happened within 3-4 minutes," said Vaibhav.
As soon as the four left, Mr Parmod shouted for help, and other neighbours came in, the staff members of the shop informed police.
Police said they received a call around 12.13 PM about the robbery. A crime team reached the spot and procured CCTV footage of nearby shops. The cameras installed inside the shop were not working but those outside were working, the police said.
Police have also collected footages from other shops in the area.
"We have also collected eight finger print samples from the spot," said an officer, adding probe was on.