The shooting happened at 9.15pm on Tuesday, March 29, when three youths opened fire at Stockwell Food & Wine Shop in South London.
Dave Cording, director of operations at Crimestoppers, said: “This is a heinous crime. For an innocent five-year-old child and 35-year-old man to receive such horrific injuries is utterly despicable.
“A reward of up to £50,000 is being offered to anyone who can supply us with information leading to the arrest and conviction of the persons responsible for this crime.
“I hope the offenders will be swiftly brought to justice and would urge anyone with information to contact Crimestoppers anonymously on 0800 555 111 or our online service at www.crimestoppers-uk.org.”
Association of Convenience Stores chief executive James Lowman said: “Our thoughts are with the victims and their families after this horrific incident. We want to help the police, through Crimestoppers, to catch those responsible and we hope that by funding this reward we will play a part in securing more information to support the police investigation.”