Three people were transported to North York General Hospital Thursday morning after being exposed to a small quantity of toxic gas in the underground parking garage of a nearby condo.

The incident happened at a building-under-construction at 68 Esther Shiner Blvd., which is near Leslie Street between Sheppard Avenue West and Highway 401.

Emergency responders were called to the area shortly before 11 a.m. and the building was promptly evacuated.

Speaking to the media at the scene, Dist. Fire Chief John Brunton said that workers were mixing epoxy in the P4 level of the parkade when that substance “went into runoff,” which essentially means that chemicals reacted and released gas.

“Due to that and being down in the underground, it caused a little bit of a toxic situation down there,” he said.

Brunton said that the three people who were taken to the hospital were “checked out” for “minor exposure to toxins.”

Toronto paramedics told CP24 that eight others were also assessed at the scene for "unknown chemical inhalation."

The runoff situation has now been addressed, Brunton noted.

“The bucket was removed out into open air, and at that point in time, it's pretty much free clear to off gas in an open area and it's pretty safe at that point,” he said.

“And with that being such a small quantity, it wasn't that much of a hazard once it got out of there.”

The fire official also said that the affected area is now clear and that their hazmat team has recorded a “zero parts reading,” adding “everyone’s been notified that needs to be notified.”

Toronto fire, in a post on X, said that Ontario’s Ministry of Labour has been advised of the incident.

An investigation will now be done to determine what happened and what kind of gas was created during the chemical reaction.