Skarr paid little attention to the newcomers. He had sized up his 'companions' earlier, but with the knowledge that Spectres were the reason behind this, he did not feel the immediate danger of betrayal that was often a cornerstone of such ominous and mysterious contracts like this. That didn't stop him from seeing how they moved, the knowledge of that now sorted into his war-torn mind just in case, for later. As for who they were? He'd care when they proved they were worth his attention. 

He switched his Assault Rifle for his Claymore Shotgun as they walked. He couldn't say that he was particularly happy that they were to merely incapacitate the Cerberus operatives, but he'd done more than a few such jobs. In fact he had often been preferred by employers for such tasks, due to his intense sense of control. Most Krogan Battlemasters would punch a man, and question later why the human's skull was so weak that their head caved in. 

He prepared a special round in his shotgun just for such an occasion, and shouldered it at the ready for when the combat would break out. The Krogan's body ready to spring, he waited... 

Skarr fired. As his companions fought around him, the Krogan's Concussive shell slammed into one of the Cerberus operatives aiming for Rykarn's back from afar. Even as the man was knocked off his feet and sent into the wall, Skarr was charging forward powerfully. He holstered his shotgun, deciding to keep himself from wasting ammunition. He closed the distance between he and the next trooper fast, only getting a small graze of a Pistol shot along his armor before he knocked the weapon flying, his other hand 'lightly' striking the trooper across the head, and then booting the man in the chest with a powerful knee. 

When the man flew, the Krogan stomped down on his same foot to halt his advance abruptly. A quick scan showed that turrets were still deploying. He grinned from within his erected helmet, and revealed his Biotic hammer. With a roar, he shifted his weight and slammed his hammer into the ground. A biotic shockwave erupted and ripped apart the ground, the wave of energy burst through two of the turrets and heavily damaging a third in the process. The last turret that was juttering, he took his time with. He strode over to it, and personally crushed it with a well placed hammer strike. 

"Are we done, here?" he asked them.