( CNN ) -- Three young women are dead and two are in serious condition after being crushed by a crowd at a Halloween party in Madrid early Thursday , police said . The women were among thousands of attendees at `` Thriller Music Park , '' an event at Madrid Arena that featured electronic music artists and a costume contest . There was a stampede in an arena hallway that connected the main dance floor to another area , police said . The five women , between 18 and 25 years old , were the only ones hurt in the incident , an ambulance spokesman said . Four of the women , including the three who died , are Spanish . The nationality of the other injured woman is unknown . Police are investigating whether someone set off fireworks in the hallway , the spokesman said . Thousands of partygoers were unaware of the stampede until after police arrived and began moving people out slowly . American electronic musician Steve Aoki was headlining the party . Aoki released a statement Thursday saying he was `` devastated '' by the deaths and injuries . `` The safety of my fans has always been my top priority and had I known that there was any distress putting people in jeopardy within the venue I would have ended my show immediately , '' Aoki said in the statement , adding that he was canceling a subsequent show in Bilbao , Spain , `` out of respect for those who lost their lives and those who are injured . ''
Three women were crushed in a stampede at a early Thursday party . two died , and Three are in serious condition . The event at Madrid Arena featured electronic music and a costume contest .