Guests were held inside Thorpe Park on Saturday evening as police responded to a serious incident.
A guest at the Surrey theme park has seriously injured another, according to the attraction.
South East Coast Ambulance Service said they were called to Thorpe Park to treat a man who had sustained an abdominal injury.
In a statement released at about 7:45pm, Thorpe Park said: “An incident took place where a guest was seriously injured by another guest.
“The resort’s fully trained security and medical staff were on scene within minutes and administered immediate care until emergency services teams arrived.”
“We are co-operating fully with the police and their ongoing investigations. We’d like to thank guests for their patience.”
Surrey Police said two men had been arrested on suspicion of attempted murder.
“Two groups of people were involved in an altercation on the bridge close to the exit and one man aged in his twenties has subsequently been treated for a slash wound to his stomach. He has been taken to hospital and his condition is described as serious,” the statement read.
“Officers have been carrying out enquiries at the scene and two men, aged in their twenties, have been arrested on suspicion of attempted murder. They remain in custody at this time.”
The police added that the incident was not being treated as terrorism-related.
‘Blood all over floor’
Eyewitness accounts on social media describe the park’s entrance and exit bridge as being the scene of the incident.
Eyewitness Tony Stone told SurreyLive: “We could see paramedics working on someone on the bridge. We have been told to come back in the park.”
He claimed to have been told to return to the main park after attempting to leave via the bridge shortly after 5pm, which was the park’s closing time.
Mr Stone added that blood was “all over the floor”, and sent SurreyLive a short video clip appearing to corroborate this, with police tape visible.
One video posted on Twitter appears to show police removing an incident screen from the area.
Ride openings were extended, before guests were eventually allowed to leave the park more than an hour after its normal closing time.