Avicii Ecstasy Triggered Mass Hospitalization At Avicii Concert

6/26/2014 12:25 PM PDT

Avicii: Ecstasy Triggered Mass Hospitalization of Fans at Boston Concert


Ecstasy played a central role in the 911 emergency Wednesday night that sent dozens of Avicii concertgoers to the hospital ... TMZ has learned.

Law enforcement sources in Boston tell TMZ ... some of the concertgoers were high on ecstasy and it created a dangerous situation, because the pit area was extremely hot and crowded.  Dehydration is a common side effect for ecstasy users.  Many of those taken to the ER were severely dehydrated.

What's unclear ... where all the concertgoers got the ecstasy and if a particular batch feuled the emergency.

One concertgoer tells TMZ ... in addition to hard drugs, the place smelled like weed and puke and some people were so wasted they were falling down stairs, urinating in the back rows, and passing out. 

In all, 36 people were taken to local hospitals and additional 50 were treated at the scene.