People can also hand in the weapons anonymously, and Nottinghamshire's Police and Crime Commissioner, Paddy Tipping, said: "We want people to be safe and secure. Every firearm surrendered is one less weapon that can be used to commit crime".
Det Supt Jennings said she knows "people involved in gangs are hardened criminals are unlikely to hand in their weapons" but she urged their loved ones to help make South Yorkshire a safer place.
Mums, sisters and girlfriends of boys and men who carry guns and knives in Sheffield are being urged to hand in the weapons in a bid to save their lives.
Members of the public are given the chance to surrender guns or other weapons safely by taking them to a police station.
"If you know where a weapon is being kept illegally, now is your chance to give up the gun, or tell us anonymously where it is".
Commander Jane Gyeford, of the City of London Police, said on Monday, November 13, she hoped people would take advantage of the surrender to hand in weapons which were in their possession.
Police officers across the United Kingdom are urging people to hand in any unwanted firearms, including handguns, shotguns and antique weapons, to "prevent them from falling into criminal hands".
It is being organised by the National Ballistic Intelligence Service (NABIS), which says many guns are held in innocence or are overlooked and forgotten in people's homes.
During the fortnight firearms licence holders are also being encouraged to consider the surrender of weapons they no longer have any use for.
Motorola Moto X4 launched in India, price starts at Rs. 20999
The smartphone gets an anodised aluminum frame encased in glass, with a 3D contoured back for a comfortable grip. The Moto Tab comes with 2GB of RAM and 32GB of expandable storage, "an ultra-slim profile" and soft-touch back.
"The surrender provides the flawless opportunity to safely dispose of these weapons and to prevent them from ending up on the streets and falling into criminals hands, which only brings destruction and devastation to our communities".
Chief Inspector Mark Colquhoun said: "Compared with other areas of the country we don't have a significant gun problem, but we are keen to support this national campaign to help keep our communities safe".
Richard Kennett, firearms licensing manager for Norfolk and Suffolk Constabularies, said the campaign had got off to a good start, with 14 guns already collected before lunchtime on Monday at police sites in Ipswich and Martlesham.
Weapons and ammunition can be surrendered at anyone of our eight staffed police stations. If the sentence was of three years or more, they are classified as a prohibited person under the Firearms Act and can never possess any type of firearm or ammunition.
Illegal possession of a firearm can mean five years behind bars and if you are found guilty of possession with intent to supply it can lead to a life sentence.
Launching the drive in the Northwest, Detective Chief Superintendent Mary Doyle, of Greater Manchester Police, said the public should be anxious about the supply of guns on the UK's streets.
If you know of people involved in illegal firearms you can call Crimestoppers on 0800 555 111; report it online at Lancashire.police.uk/report it; or call 101.
If someone is unable to travel to a police station they should contact police via 101 and arrange for the firearm to be collected.