The shocks happened in quick succession.
The first two dogs were killed. The third bit its female owner, as well as a passer-by who tried to assist, police said.
The owner flagged down a passing police cruiser. When the officer touched a metal part of the injured dog's collar, she was also shocked, with the current travelling up her arm. She was taken to hospital as a precaution, while the dog was taken to a veterinarian.
The problem was caused by a faulty insulator in a span cable that holds up the mass of streetcar wires over the intersection. When the insulator failed, it caused an electrical current to pass from the streetcar wire into the span cable and from the cable into a metal pole it happened to be touching.
From the pole, the current travelled into the sidewalk, conducted by the rain.
Hydro crews cut power and cordoned off the area, while TTC repair workers fixed the insulator and moved the span wire clear of the pole.
The streetcar service had returned to normal in the area within hours.
"I would offer our sincere sympathies to the pet owners and a speedy recovery to the police officer as well," said TTC spokesman Brad Ross.