Since it was just her third day on the job, Tracy Downer rode along with a co-worker to learn more about her new advertising role.

It made sense, since Michelle Chinnis had been with the company since 2004.

But before they could take a lunch break, the two women were killed Wednesday morning when Chinnis's car was struck by a tractor-trailer that witnesses said ran a red light on Thornton Road in Douglas County.

Downer, 44, of Atlanta, died at the scene of the massive crash, according to the Georgia State Patrol. Chinnis, 35, of Smyrna had to be extricated from the wreckage and later died.

Four people in other cars were also injured. The driver of the tractor-trailer, 64-year-old Robert John Sansom, of Colorado, was not injured, according to troopers. No citations had been issued as of Thursday evening, as the GSP continued to investigate the accident.

Both Chinnis and Downer worked in sales for AutoTrader.com, a website owned by Cox Enterprises, which also owns The Atlanta Journal-Constitution.

During her time with the company, Chinnis held a variety of positions, including customer operations before become an advertising specialist in 2008, the company said in a statement released to employees. Downer had just joined AutoTrader.com on Monday as an advertising consultant. Prior to her new job, Downer worked in advertising at the AJC from 1993 to 2010, company leaders said.

On Thursday, the women's two families were preparing for their funerals. Co-workers planned a memorial for Friday.

Downer was married with a son and a daughter, and Chinnis is survived by a 16-year-old daughter.

Viewing services for Chinnis will be held Saturday from 9 to 11 a.m. at Gregory Levett and Sons Funeral Home on Scenic Highway in Lawrenceville. The funeral will follow at 11 a.m. at the funeral home.

Funeral plans for Downer were posted Thursday on her Facebook page, which is public and can be viewed by others. Visitation will be Sunday from 2 to 6 p.m. at Patterson Funeral Home in Atlanta, followed by a mass Monday, at 10 a.m. at the Cathedral of Christ the King, also in Atlanta. A reception will follow at the church. A memorial service will be held the following week in Illinois.