15 minutes before she died in a car accident, Tammy posted an ominous Facebook status.

An 18-year-old woman, who was killed when the car she was a passenger in collided with a tree in South Australia, posted an ominous message to Facebook in the moments before she died.

Tammy Marchant, a mum-of-one, was on a roadtrip from Western Australia with Josh Graham, 26, Aaron Bishop, 20, and Jarrad James Famlonga, 24. The Nissan 4WD they were travelling in rolled on Augusta Highway in the early hours of Thursday morning, killing Merchant and her friend Graham who was driving at the time.

Just 15 minutes before the crash at 12.15am, Marchant wrote on Facebook what would come to be her last ever post on social media.

“This trip has definitely made me realise take all the chances and memories you have because you don’t when it could be your last,” her eerie words read.

“You spoke to soon girl [sic],” one friend later commented.

Those words were part of a bigger tribute to her pet dog Troy.

“I miss my boy Troy, so much why does the heaven always take the good ones so quick it’s been 4/5 months now with out you and to be honest I thought it would get easier! But you were the best thing I’ve had since I was 10! I’ll forever love you,” she wrote at the time.

On Thursday, 20-year-old Aaron Bishop, who was travelling the back seat Jarrad James Famlonga, gave a harrowing account of his hazy memory of the crash in a status on Facebook.

Tammy Marchant and Aaron Bishop. Image: Facebook.

"Last night we were driving to Adelaide where I woke up from the back seat to see the car heading for the tree's in the middle of the freeway, I blacked out and when it all stopped I just screamed, I kicked the window through with my feet not hearing any of the other 3, my first instinct was run out on the freeway and play chicken until someone pulled over to help, covered in blood, of course heaps of people never stopped to help.

"Finally got help where Tammy and [Josh] had died on impact, Jarrad managed to wake up and I helped him out, we were air lifted to Adelaide hospital, I'm fine, just very, very sore, hurt, and tired, few stitches in my eye but that don't bother me. I just miss them 2, I want them back so much its killing me, I'm so sorry everyone, I really am... Rest in paradise to 2 of my most favourite people ever," he wrote.

Bishop also said he and Famlonga were "physically feeling a lot better" after the crash.

If you would like to donate to the families of Tammy and Josh, there is a fundraiser on GoFundMe here.