A concert by dance music star Skrillex was marred when 16 fans were hospitalised after taking drugs.
Paramedics treated several concert-goers at the show in at Chicago's Navy Pier venue on Saturday (18Oct14).
It is not known what condition the victims were in or what substances they had consumed.
Andrew Bazos, security chief for the show's promoters Sfx, tells NBC Chicago, "They're young, and they're often irresponsible."
A spokesman for Sfx insisted the promoters do all they can to curb drug-taking at concerts, adding, "We're very strict at the doors so that people don't bring bad things in."