One person was killed and seven were injured in a roller coaster accident at the Grona Lund amusement park in the Swedish capital on Sunday, the TT news agency reported, citing a park spokesperson.
Public broadcaster SVT, citing eyewitnesses, said the park's Jetline roller coaster had partly derailed during a ride.
Ambulances, fire trucks and a helicopter were seen arriving at the park, and police said they were investigating.
"We are emptying the park and we've started our investigation," a police spokesperson said.
Grona Lund said in a statement the 140-year-old park was closed until further notice. A spokesperson could not immediately be reached for comment.
What caused the accident?
Jenny Lagerstedt, a journalist visiting the park with her family, told SVT she was nearby and heard a metallic noise and noticed the track structure was shaking at the time of the accident.
"My husband saw a roller coaster car with people in it falling to the ground," Lagerstedt said.
"My children were scared," she added.
The steel-tracked Jetline roller coaster reaches a speed of up to 90 kilometres per hour (56 mph) and a height of 30 metres (98 feet), transporting more than one million visitors each year, the amusement park says on its website.