'Not something anyone has ever seen': Hydro One investigates how a barge and crane left Toronto in the dark

A day after a power outage left thousands in the dark in downtown Toronto for nearly eight hours, Hydro One says it is continuing to assess damage caused by a crane that hit high-voltage power lines.

Toronto Hydro and Hydro One say power was restored last night to remaining customers after a large swath of the city's downtown core — including office buildings, a major mall and a university campus  — was left without electricity.

Hydro One says the outage was caused by a barge moving a crane in an upright position that ran into high-voltage transmission lines in the Port Lands, a largely industrial area on Toronto's waterfront. 

"There are safe limits any time you are talking about power lines and the [person operating the boat] was clearly not adhering to that," said Hydro One spokesperson Tiz Baccega Rosa told CBC Radio's Metro Morning on Friday.

"I've been around for 10 years, a lot of long-standing employees at our company know this is not something anyone has ever seen."

The outage, which hit around 12:30 p.m., affected approximately 10,000 customers, and power was restored to half of them by 6 p.m. It affected customers in the financial district, Toronto Metropolitan University and the bustling Eaton Centre mall.

"That type of impact on a line carrying that voltage actually has a downstream effect that was hindering our ability to repower," she said.

Baccega Rosa said the incident, which caused issues at its Esplanade station, meant crews also had to wait for Toronto Fire to determine the site was safe before they were able to enter and re-route power.

"A lot of yesterday was spent actually gaining safe access to the site. Once they were able to gain access to the site, [crews] were able to make repairs," she said.

At approximately 8 p.m., Toronto Hydro reported that all affected customers had their power restored. 

Baccega Rosa said Hydro One crews will continue to assess damage on Friday.

"The important thing to know is what is happening shouldn't have an impact on the city," she said.

The City of Toronto says it has launched a full investigation into the cause of Thursday's massive power outage.

The city has said a subcontractor at Toronto's main wastewater treatment plant may have been responsible.