The bandit group was getting ready to escape. They turned back from they were coming from and ran away.
Auron was still fighting against the monster. He didn't realize there were spectators. Only after the bandit group started to escape did Auron realized the bandit group's presence.
In a sudden split second, a thought flashed in Auron's mind, "F***, My secret exposed!"
There were actually many possibilities that could happen. However, the one that came to Auron's mind was the worst possibilities.
If Auron's secret was exposed, then there would be no doubt that he would be dead. Auron would be chased all over the place. Also, if the news was spread to others, then many enemies would pursue him.
He needed to stop the bandit. Auron immediately ignored the monster he was fighting against and chased the bandit.