Friends posted this photo of Heather Rae Thurier, 23, to an online memorial group. (Facebook)

About 20 people gathered outside an Edmonton LRT station to remember Heather Rae Thurier, who was fatally shot in the head.

Thurier, 23, was killed Friday night after what police say was a conversation that escalated into a confrontation at the Stadium LRT station.

Nicole Gladue, Thurier's older sister, organized a vigil on Monday afternoon where she and other family and friends lit candles, burned tobacco and prayed for Thurier.

"I know a piece of everyone in my family has died with her," Gladue told reporters through tears.

She described her sister as a calm, gentle person who leaves behind two children under three years old.

Nicole Gladue, left, organized Monday's vigil in memory of her slain younger sister. (CBC)

"I have anger for [the shooter] because he stole my niece's and nephew's mommy right from them," she said.

Gladue said she believes her sister's death stemmed from a simple request for a cigarette.

Police, who are still looking for a suspect, have not yet established a motive for the shooting. Investigators are poring over surveillance tape from the station.

"I'm afraid for my safety, my family's safety. I'm afraid for the general public even. The guy's still at large," said Gladue.

Police said they're looking for a man between 16 and 21 years old, about five feet 10 inches tall and weighing around 160 pounds. He was wearing a dark hooded sweatshirt, dark jeans and a baseball cap.

With files from the CBC's Min Dhariwal