Paramedics performed emergency surgery on a 66-year-old man at the scene, but he suffered a cardiac arrest and was pronounced dead.
His brother, who is in his 70s, also suffered chest injuries.
He was airlifted to Frenchay Hospital near Bristol, where he remains (Tuesday).
More top news
The Royal Bath and West is celebrating 50 years at the showground near Shepton Mallet. Here's a taster, including Downton's Julian Fellowes
Bristol were 6 points ahead on aggregate until a last minute converted try sent Worcester back to the top flight at the first attempt.
Britain's oldest groundsman is offering his life savings to save a local football club which will fold on Sunday unless a solution is found