Five ambulances are on duty for a medical incident in SkyCity Auckland. Video / Dean Purcell

The drug behind a public overdose in downtown Auckland yesterday is now under forensic investigation by government scientists.

Police this morning confirmed that the seized substance, which resulted in an overdose of three people outside of Auckland’s SkyCity yesterday morning, had been sent to ESR for testing, a police media spokesman said.

Meanwhile, the three people – two men and one woman – who are said to have overdosed on a synthetic substance, are recovering at the Auckland hospital.

In a statement yesterday, SkyCity said St. John and the police were called after a staff member noticed three people were unwell.

“The three people were taken to the hospital by ambulance.

“The matter is now in the hands of the police.”

At around 8:30 a.m., the police and several ambulances were on duty.

Witnesses reported seizures and fainting.

“You just passed out. It wasn’t good. You were incoherent, so to speak,” said a man who was sitting in front of SkyCity asking for a change.

Last month, Wellington Police warned the public about a rare and highly dangerous methamphetamine-like substitute called isopropylbenzylamine that could be making the rounds.