One female has died of an apparent drug overdose following an all-ages event at Rebel nightclub in Toronto.

Toronto police said they responded to the nightclub, located on Polson Pier, late Friday night for a total of six reports of suspected overdoses.

Paramedics, who were hired by the nightclub to be on standby at the event, treated one person on scene for overdose-related symptoms while four others refused treatment.

One female was rushed to hospital via emergency run where she later died. Her age is still unclear.

Const. David Hopkinson told CTV News Toronto that several club goers exhibiting symptoms were not taken to hospital and were advised to drink water and sit down.

He said they refused to answer questions about the incident when police arrived.

Investigators won’t be able to determine what kind of drugs the deceased female took until a full toxicology report is conducted.

Hopkinson added that it’s too early in the investigation to determine whether the overdose was a result of an illicit drug or prescription medication.

“When you look at the venue, it holds approximately 4,000 people, that’s a significant number of people. It’s a concert we’re talking about,” Hopkinson said Monday. “Somebody has died, (but) from what? We have no idea. We have to wait for toxicology. Once that comes in, then we might be able to go back and look at what we might have done to stop it. Was this an allergic reaction? We don’t know. What type of drug did they take, if it was a drug that they took? We don’t know.”

A police source told CTV News Toronto that the call for the deceased woman came in just after midnight and a friend of the woman told police she had taken MDMA, a drug also known as Molly.

“I didn’t see anyone passing anything around, but at the end of the night there were a lot of drug bags on the ground,” Samantha Redman, who was at the venue last night, told CTV News Toronto.

Redman said she saw two young women collapse inside the club Friday night.

“This younger blond, I don't know how old she was, she collapsed in front of us. All of her friends didn't notice until a couple minutes after. We were really scared, wondering where is the security. One of her friends went to get security. But when security went to lift her up…she was shaking on the ground,” Redman said.

In a statement released Monday evening, the nightclub said drugs are not allowed at its events.

“We extend our sincerest condolences to the family and friends of the patron who passed away, and will keep them in our prayers during this difficult time,” the statement read.

“Rebel has a zero tolerance drug policy, and also subjects every patron entering the venue to a full search. Anyone who is caught with an illegal substance is immediately denied entry. We employ an EMS company on-site for every music concert and club night."

According to a Facebook event page, Toronto-based electronic music duo DVBBS were performing at the club Friday night. A poster for the event indicates all ages were welcome.

Police said the owners of the nightclub are not currently being investigated in relation to the incident.