A worker plunged about 30ft in a horror fall as he helped to set up a roller coaster for a Winter Wonderland fairground.
A shocked witness told how the man "wobbled and fell" and was "shouting and screaming" as he lay injured after landing on the ground at the site in Stoke-on-Trent.
Another witness said he was waiting for a bus when he saw the man fall - claiming the worker "just stepped off and went straight down" - and then heard a sickening "thud".
It was claimed the worker was not wearing a safety harness when he plunged from the unfinished ride on Saturday afternoon, StokeonTrentLive reports.
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The man was rushed to hospital, but his condition was not immediately available.
An air ambulance landed nearby, but the man went to hospital in a land ambulance, according to witnesses.
Tina Robinson, 52, was parked nearby while picking up her two daughters when she witnessed the incident.
She said: "As I glanced up I saw a man on top of a roller coaster helping to put it up and suddenly he wobbled and fell.
“I ran round to see what had happened and there were two other workman with the man who was lying on the floor shouting and screaming. It was awful. It made me feel sick.
“I then heard the sirens. The police arrived within minutes and then the first responder arrived. As I left I saw more emergency services arriving. I just hope he is going to be OK.”
Another witness, Paul Hodgkinson, 44, said: “I was stood here, by the old bus station, when a man on top of the double roller coaster just stepped off and went straight down.
“He was obviously in a bad way.
“He never had a harness on.
“The air ambulance came but he went in the land ambulance.
“It was a shocking thing to see. The sound of the thud is not something you want to hear.
“He was screaming at first but then it just went quiet.”
Frank Dale, 66, added: “I just came to have a look at them putting up the fairground and then that happened. It left me shocked.
“It was poor from a health and safety point of view. He was not wearing a harness. If he had been he would have still been on there.
“Let’s hope he is OK.”
