A fire in an underground hydro vault prompted the closure of a small section of the downtown core and caused power to the Eaton Centre and some of the surrounding area to be shut off Saturday afternoon.

The blaze broke out around 1:30pm under Richmond Street near Yonge when a ball of flame and toxic smoke shot from a grate on Richmond Street.

"We think that there was a short or one of the transformers defected," said Toronto Hydro spokesperson Tanya Bruckmueller.

"It caused a fire which in fact ended up burning through all of our cable and much of the vault underground."

Hydro crews arrived on the scene a short time later, and though only one commercial customer initially suffered the loss of power, shortly before 5pm the juice was cut to the Eaton Centre while p olice closed Richmond to vehicle and pedestrian traffic between Yonge and Bay Streets and on Bay Street between King and Queen as a safety precaution.

Thankfully, no injuries were reported, though some Eaton Centre patrons were shaken when the lights were suddenly cut.

"We were kind of freaked out a first we didn't really know what was going on," said Jessica Chapman, who was inside the mall at the time the power went out.

Power was expected to be out for at least two hours, but by late Saturday crews were still working to restore it to portions of the area.

There were also reports of people directing traffic at some intersections as several street lights were also out. Edmond Chano was one such individual.

"I'm using my broken umbrella to keep everybody safe," the Good Samaritan said.

"I got insulted, I got the finger and I got compliments."

Hydro officials believe the wet weather may have washed salt debris into the underground electrical equipment and sparked the blaze.

"Until we get in there we won't be sure but we're assuming that at this time of year when spring comes around generally debris and salt that gets down into our vaults can cause a shorting and then therefore a fire," Bruckmueller said.