Police say a woman has died from her injuries after being struck by a 15-year-old bicyclist on a Scarborough sidewalk last Thursday.

The 56-year-old woman, who has not been identified, died late Friday night.

Det. Const. Lester Lalla said the cyclist likely will not face criminal charges, but could be held accountable for breaking city bylaws if police find he was riding an adult-sized bike.

"There's no criminal element; it's just one of these accidents," Lalla told ctvtoronto.ca.

"Riding on the sidewalk, there are certain criteria that a bicycle falls on. If it's a regular-sized bicycle they should be using the roadway."

Investigators will measure the size of the bike's tires to see if they are less than 61 centimetres in diameter.

The collision happened Thursday afternoon on the west sidewalk of Kennedy Road, near Sheppard Avenue East.

"For whatever reasons, they get closer to each other and there's some miscommunication," said Lalla. "He tries to go around her, she sees he's coming and she goes to avoid the cyclist, and they both go into the same path of each other."

He said the teenager went over the handlebars and struck the ground, while the woman fell and appears to have struck her head on the sidewalk.

Lalla said it's very rare for a pedestrian to die in a collision with a bicycle -- so rare that he could not recall any similar incidents in Toronto.