Three young women have been killed and two are in a critical condition after getting caught in a stampede during a public Halloween party in Madrid, emergency services say.
It was not immediately known what caused the crush at the party early on Thursday, which featured electronic music and was held at the Madrid Arena in the west of the Spanish capital, Reuters reports.
However, reports suggest the panic began after a flare was thrown into the crowd.
One partygoer told Spanish radio there was only one exit open at the venue, which can house 10,000, and that the others were sealed off.
Two of the victims were 18 years old, while the third was 25, police say.
Meanwhile, a man is in a critical condition at an Irish hospital after his Halloween costume caught fire at a nightclub in the city of Galway.
Four wounded in US shooting
At least four people have been wounded in a shooting incident at a Halloween party at the University of Southern California in Los Angeles.
The incident is reported to have taken place at 11.30pm on Wednesday (local time). At least one suspect has been detained, the BBC reports.
The university shut down the campus and urged students to stay away from the area of the shooting, amid earlier reports of a gunman at large.
Witnesses reported a "mob of people" fleeing from the main campus building.
In 2008, University of Southern California sprinter Bryshon Nellum was shot in the leg three times at a Halloween party just off the campus.
He recovered and won a silver medal in the 4 x 400m relay at this year's London Olympics.