A businessman found a threat letter and two live cartridges inside a sweet box outside his house in southwest Delhi's Vasant Vihar area, police said on Saturday.
A case under section 506 (criminal intimidation) of IPC and section 25 of the Arms Act has been registered against unknown persons and investigations started, they said.
The businessman approached the local police on Friday afternoon after he received the box, an officer said.
"On opening the sweet box, he found two live cartridges with sweets and a handwritten threat letter with some personal comments written on it," the officer said.
"It is suspected that some personal enmity is the reason behind the threat," the officer said, adding that they are investigating the case from all possible angles.
Another officer said CCTV cameras installed outside the businessman's house are being analysed to narrow down on suspects.
"A few people have been rounded up and teams are working on multiple leads," Deputy Commissioner of Police (southwest) Rohit Meena said.
