"Our No1 priority is the safety of our drivers and officials," V8 Supercars boss James Warburton said. "Our thoughts are with Chaz and his family and the marshals who do an incredible job."
Mostert's parents, Eddie and Maree, were present in the team garage during the crash.
It marked Mostert's second horror crash in three years on the mountain.
Mostert emerged unscathed when he made heavy contact at Reid Park with his Ford in 2013 practice on his Bathurst 1000 debut.
Last year, he won the Great Race with Paul Morris in a famous last-to-first effort.
"First of all, we hope Chaz is all right. He's got to get back on the horse, but it's a pretty powerful horse," two-time Bathurst champion Russell Ingall told Seven Network.
"This may relive memories [of previous crash for Mostert]."
V8 Supercars officials are yet to release today's rejigged qualifying schedule.
Earlier, defending V8 Supercars champion Jamie Whincup clocked the fastest lap at Mt Panorama. He was timed at two minutes, 04.90 seconds in the last session before qualifying - more than half a second faster than Holden's Fabian Coulthard's practice effort on Thursday.
He finished ahead of Ford's Scott Pye (2:05.24), who will partner two-time series champion Marcos Ambrose.
The build-up for the Bathurst 1000 has been full of off-track stories around the return of Marcos Ambrose to Mt Panorama, the first all-women pairing, IndyCar driver Simona De Silvestro and Renee Gracie, in 17 years and David Reynolds' inappropriate comments about the female pairing.
All that now stops as the main game drivers and their co-pilots focus on the task at hand the all-important top 10 shoot out. Any driver worth his, or her, salt loves to have the bragging rights of starting the Great Race from pole. However, if you dig a bit deeper it's all about what their track position is when the chequered flag comes out at 8pm tomorrow.
After years of being a bit hit-and-miss, the Fords under the guidance of Prodrive Racing Australia have come good, especially in the hands of Mark Winterbottom, Mostert and David Reynolds who just happen to be one, two and three in the title race.
All three sit inside the top five (second, third and fourth), and are book-ended by Kiwis Fabian Coulthard and Shane van Gisbergen. Coulthard has always been fast on the mountain, but results so far haven't fallen his and co-driver Luke Youlden's way yet.
Coulthard is quite keen to exorcise a few Bathurst demons and knows if a bit of luck falls his way he'll be on the podium.
"All I need is a little bit of luck and we'll be okay [good result]," said Coulthard. "We've always been fast enough most years we've been here, but haven't had that little bit of luck you need to get on the podium.
"I love Bathurst and it's the best event on the calendar by far. The car's been quick this year and we've had podiums at most events as well. We're fifth in the championship and in the hunt. There's a lot of points on offer this weekend and we need to be in them."
Another who will be looking to put some baggage away is fellow Kiwi Scott McLaughlin who's paired with Frenchman Alex Premat. The Volvo pair looked to have the race pretty much squared away last year having been in front for the majority of the event. It all came unstuck unfortunately towards the end of the race when McLaughlin clipped the wall at the Cutting.
The team have struggled this year to get the car to be fast and reliable.
Sandown was yet another hiccup in 2015 when Premat pulled out of his pit box with the air hose still attached resulting in another pitstop. This frustrating year must be playing on McLaughlin's mind, but he's upbeat about his chances this weekend.
"The car feels really good in the races and I genuinely think we have a good chance [to win] this weekend. We're flying a bit under the radar at the moment and I'm really looking forward to the race.
"We led for most of the race last year and the car's always good here. It's important for us to stay on the ball and don't stuff about."
One of the dark horses in the race will be the fledgling team and pairing of young Kiwis Andre Heimgartner and Ant Pedersen. They were the surprise package at Bathurst last year by staying out of trouble and being on the lead lap at the end. Finishing 11th was a damn good result in Super Black Racing's inaugural attempt at conquering Mt Panorama.
"I can't wait to get racing again [Bathurst]," said Pedersen. "We had a good result last year where we just focused on ourselves, [and if we] stayed on the lead lap and made the finish we would be in the [top] 15.
"If you keep your nose clean through the majority of the race you'll always be in a good spot at the end.
The final New Zealander in the field, van Gisbergen, and co-driver Jonathon Webb will be definite contenders come tomorrow afternoon.
5 picks for the Great Race
1. Mark Winterbottom and Steve Owen
Winterbottom is the form driver of this year's V8 Supercars championship and is a former winner of the Great Race. The pair finished first at Sandown last month in a car that is finally working, so will be hard to beat.
2. Jaime Whincup and Paul Dumbrell
Defending V8 Supercars' champion Whincup is struggling, by his standards, this year. But it appears the Triple Eight crew has finally found some speed for the pair, as shown at Sandown, so they could be the pairing to beat.
3. Shane van Gisbergen and Jonathon Webb
Neither driver has a Bathurst to their name - yet. Having to retire from leading the race in its dying stages will still hurt and will be a great motivator for 2015.
4. Craig Lowndes and Steven Richards
A combined total of eight Bathurst 1000 wins shows they know how to get the job done. Lowndes is in the overall championship contention, so will be keen to grab the 300 points to set himself up for the run in to the season end.
5. Chaz Mostert and Cameron Waters
Mostert has been in scintillating form this season, and is the only driver to consistently challenge Winterbottom for pace. He followed his teammate home at Sandown, and is second to Winterbottom in the championship.
Points (after 9 rounds)
1. Mark Winterbottom 2295
2. Chaz Mostert 2017
3. David Reynolds 1855
4. Craig Lowndes 1792
5. Fabian Coulthard 16940
6. Garth Tander 1634
7. Shane van Gisbergen 1620
8. Jamie Whincup 1586
- additional reporting AAP
