About 150 seniors will be out of their home tonight, allowing officials to investigate a gas leak at a retirement residence that sent five people to hospital earlier in the day.

Some of the seniors will be transported by TTC buses or WheelTrans vehicles to other retirement homes operated by Leisureworld. Others will stay with family until their accomodations are deemed safe again.

The seniors were forced out of the building at 1800 O'Connor Dr. at around 10:45 a.m. when a handful of staff members working in the kitchen fell ill.

They were transported to hospital and treated for carbon monoxide poisoning. They are expected to make a full recovery.

The building has been ventilated and air quality levels are being checked.

High carbon monoxide levels were recorded inside the building at the time of the evacuation, EMS officials said.

The source of the carbon monoxide leak is being investigated.

O'Connor Drive is closed between Sunrise and Victoria Park avenues.