One person was killed and several 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.
Police said they were still investigating.
"We are emptying the park and we've started our investigation," a police spokesperson said.
The Grona Lund park was not immediately available for comment.
The steel-tracked Jetline roller coaster reaches a speed of up to 90 kmph and a height of 30 metres, transporting more than one million visitors each year, the amusement park says on its website.