BRADLEY COUNTY, TN.  (WRCB)  --  We are learning more Monday about the woman shot to death by a Bradley County deputy Saturday.

People who know 30-year-old Armetta Foster describe her as a caring mother of two, but deputies say she tried to stab an officer and stole his patrol car to get away.

It all started when a deputy stopped to check on Foster as she and her two children walked along I-75 near Cleveland, for some unknown reason.

Officials say the deputy had no choice but to open fire.  Foster's cousin tells Channel 3 she was taking her son and daughter to Kentucky for a summer with their grandmother, but she was doing it in a stolen car.

The scene along Interstate 75 Saturday afternoon was unexpected, to everyone involved. From witnesses, to officials and especially to 30-year-old Armetta Foster's family.

"She was very flamboyant girl," says Foster's cousin, Nicole Foster.  "She was very into her kids, basically like a stay at home mom." 

So why would a devoted mom steal a car in Florida then ditch it on I-75, try to stab a deputy, before taking off in his patrol car leaving her 10-year-old daughter and 7-year-old son behind.

"We're just trying to find some answers about what could have triggered all of this to happen," says Nicole Foster.  "What did she have going on that we didn't know about?" 

Relatives in Sanford Florida are also asking others questions, like why did Deputy Dustin Patrick feel firing on Foster was necessary?

"It was a public safety issue," says Bob Gault, spokesperson for the Bradley County Sheriff's Office.  "We feel his actions were justified.  He tried to stop a situation that could have injured others, the weapons in the vehicle are far more deadly that the knife she was carrying." 

The police report says Foster tried to stab Deputy Patrick several times and he was, "in fear for his life and the life of others on the interstate".

"She was just trying to get some other things established like going back to school," says Nicole Foster.  "Getting a better job." 

Foster's two children witnessed the shooting, then watched their mother crash the patrol car on Old Harrison Pike road.  Grandparents will likely take them next.

"I believe something was going on with her," says Nicole Foster.  "Something made her think she had to defend herself against that officer."

According to the Bradley County Sheriff's Office the initial investigation indicates that Deputy Patrick complied with the Bradley County Sheriff's Office Use of Deadly Force Policies which are based on Tennessee State Laws.

The policy manual states deputies are authorized to use deadly force to protect themselves or others from what is, 'reasonably believed to be a threat of serious harm.  To prevent the escape of a fleeing felon who could pose a threat to others.'

An autopsy was conducted on the body of Armetta Foster Monday.  Officials are hoping, the results will lend information that might explain why she attacked.