Organizers of last weekend's Escapade music festival at Lansdowne Park are celebrating a relatively successful event with few medical emergencies, but at least one incident was very serious, and may have involved a notorious drug that's catching on with partygoers.

It happened around 7:30 p.m. Sunday during a performance by Black Tiger Sex Machine, after thunderstorms forced the concert indoors to the TD Place Arena.

Witnesses said a 21-year-old man jumped from the stands and landed on the arena's concrete floor, where he smashed his head and appeared to go into a seizure.

Other festivalgoers alerted security staff, who rushed into the crowd to help the man.

"There was a lot of blood.... I just want to know if anyone has heard if he's OK," one witness posted on Reddit. "He looked to be in bad shape."

The man, who suffered head lacerations, became "extremely combative" and had to be sedated before being transported to hospital, according to Ottawa Paramedic Service spokesperson Marc-Antoine Deschamps, who was at the festival throughout the weekend.

Deschamps said the man appeared to have overdosed on GHB, a popular drug at raves that's also known as the date rape drug because it's sometimes used to incapacitate victims.

The man could have taken other drugs as well, Deschamps said, but he's expected to make a full recovery.

Witnesses said the man wasn't the only one trying to get onto the arena floor after the concert was moved indoors.

Witnesses called security to help the injured man during a performance by Black Tiger Sex Machine. (Twitter/BTSM) "Security really tried their best to keep people from jumping that dangerous gap, but this one was out of their control," said Emma Bouchard.

DJ warned crowd

Deschamps said a DJ warned the crowd not to jump from the stands, and paramedics had already warned concertgoers about bodysurfing.

The incident was the most serious case paramedics dealt with during the two-day festival.

In total, 18 partygoers received medical treatment, 10 of them for conditions related to drugs or alcohol. One person slipped and broke a leg, according to paramedics.

Paramedics and festival staff were equipped with naloxone, the antidote used to treat opioid overdoses, but none was administered during the festival.