Alex had his bag off his back by the time he had reached the car and dumped it on the ground when the other man had passed them and gasped his warning, doing a double take as he was running at an inhuman speed. Great, he was in the company of The Flash and She Hulk, sans the green skin (so dubbed because she appeared to have anger issues). He ducked behind the car, hoping that the monster hadn't seen him and would continue after the guy and temporarily shoving the woman from his mind. The only thing of concern to him at that moment was putting the creature out of its, or their, misery.
With the bag no longer hindering him, Alex shrugged off his rifle and turned the safety off before aiming at the monster. He wasn't sure how long the man could run like that and frankly, he didn't want to risk finding out. Squeezing the trigger, he watched as the bullet exploded through the monster's ankle, making the monster stumble forward and lose interest in the other man.
The monster turned and began to advance on Alex once again but this time, it was going much more slowly which would buy him plenty of time to finish the thing off. He yanked out the spent cartridge and stood while pulling on the bolt to advance the next bullet and aimed for the creature's head. "Please just let it take one," Alex murmured and once again pulled the trigger. The bullet entered the monster's forehead and it staggered, giving Alex enough time to advance another bullet into the chamber and unloading it into its head for good measure. The thing pitched forward and fell on its face a few feet away from him, seemingly dead... at least for the time being.
Alex let out a breath he didn't realize he had been suppressing and stepped around the downed creature before picking up his bag and slung it over his back, this time without covering his rifle. He gave the monster one last look, tempted to get closer and see just what had been lodged into its face earlier, but he decided not to take that chance and looked around for the other two survivors.