Eyewitness reports hearing gunshotpublished at 13:47 British Summer Time 7 September 2020
Local resident Andy Watts told BBC Look East he was walking his dog near the area and "heard a gunshot and then I heard a great big scream".
"That's all I can say. It was a quick as that. It sounded like scaffolding falling down originally because it was a big, big crash," he said.
"I saw them working on the young lad over on the green, he was over there for quite a while, while they were attending to him, a lot of ambulance staff and paramedics working on him."