Police said alcohol and drug usage, including PCP, LSD, ecstasy and marijuana, was pervasive at the Identity Festival concert at Comcast Center in Mansfield Thursday, The Boston Globe reported.
The deaths of Dominic Impelizzieri, 27, and Connor Brandon, 19, at the concert were related to drug and alcohol use, Mansfield Police Chief Arthur M. O'Neill said Friday.
O'Neill said about 20 others were hospitalized and 45 people were arrested on various drug and alcohol charges.
"It was a return to the '70s," O'Neill said of the drug use and drinking at the show.
Live Nation, which owns the Comcast Center, confirmed that a number of people needed medical treatment during the show and that they were "aware of two people who unfortunately have passed away, and our thoughts and prayers go out to their families and friends for their loss."
Live Nation did not comment on security at the amphitheater, or how the drugs and alcohol were brought in.