The sister of a woman who was shot and killed at an Edmonton LRT station says she believes her sister's killer may have been involved in gang activity.

Police say the 23-year-old woman was found dead at the Stadium LRT station at about 10:20 p.m. MT on Friday. Police responded after reports of gunshots.

Police say the victim suffered "significant head trauma." She was pronounced dead at the scene.

Police have not released the woman's name, but her family has identified her as Heather Thurier.

Thurier's older sister Nicole Gladue describes her as a gentle soul who was a good mother to her two children, ages one and three.

"Everyone loves her. We'll always love her and we'll seriously miss her. She was like the glue in the family … she kept us all together."

Gladue said she's still struggling to come to terms with her sister's death.

"Why? There was no reason at all to hurt my sister — not hurt her, but kill her. To look at her … and then just pull the trigger."

Gladue feels her sister's death was premeditated and believes the killer may have had gang ties.

She said she's anxious to see the person responsible behind bars.

"I don't want to see him on the street anymore. I mean, I have kids out there, I have cousins, I have aunts, uncles — I don't feel safe for anybody right now."

Police seek suspect

Police have not established a motive for the killing nor do they have a suspect in custody.

"Preliminary information is that investigators believe there was a conversation between the victim and the suspect," said Edmonton police spokesperson Dean Parthenis.

"At some point during the conversation it may have escalated to a confrontation of sorts, and then very quickly a gun was pulled out, a shot was fired and the victim fell to the ground."

Police have interviewed several witnesses and seized surveillance tape.

"Investigators are feverishly going through surveillance footage," Parthenis said.

"They're hoping to possibly identifying the suspect. This could be key to helping investigators solve the case."

Investigators are trying to track down a suspect, described as a male 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.