A seven-year-old girl is "traumatized" and her mother nursing injuries after being thrown to the ground by a gunman demanding her purse and car keys -- before making off in a bystander's vehicle at a busy west-end strip mall.

Police are now pleading with the public to help them track down the armed carjacker who fled the scene near 170 Street and 99 Avenue just before 8 p.m. Tuesday.

Cops say the 46-year-old woman and her young daughter were exiting the Chapters Book Store around 7:50 p.m., and were walking towards their vehicle when they were approached by the assailant who demanded the woman hand over her purse and car keys.

"She was fortunate enough to steer her daughter to safety," said acting Sgt. Neil Thompson.

"In the course of this, the female was assaulted; punched and then kicked to the ground. The suspect was interrupted by a bystander who attempted to intervene, and threw the suspect away from the victim and her daughter."

At one point, the man dropped the gun on the sidewalk, before picking it up and resuming the assault, Thompson said.

The gunman turned his weapon on the well-intending 56-year-old bystander, threatening him before jumping behind the wheel of the man's blue 2009 Toyota Venza, and fleeing the scene.

Thompson said while the efforts of the bystander are appreciated, he doesn't recommend that people put their own lives at risk.

"It's important for people to remove yourself from the situation, and call 911, and above all make sure you're safe," he said.

"Also, people should know that they can call 911 and put it in their pocket or put the phone down if it's unsafe to talk, and we'll be able to track it and find them."

The carjacker is about five foot nine with a stocky build, in his mid-20s with short brown hair and a moustache with a goatee.

He was wearing a black parka-type jacket with a grey hood underneath, blue jeans and white running shoes.

The stolen Toyota bears licence plate ZGG 418.

Cops ask citizens to call 911 if they see the stolen vehicle, and warn the public not to approach as the wanted man is considered armed and dangerous.

Anyone with information is asked to contact the Edmonton Police Service at 780-423-4567 or #377 from a mobile phone. Anonymous information can be submitted to Crime Stoppers at 1-800-222-8477 or online at www.tipsubmit.com/start.html

allison.salz@sunmedia.ca

@SUNAllisonSalz