At first Zach was about to relax since Luke knew the people. But then he witnessed the color on Luke's face shifting abruptly as if he had figured out the complete plot just then, Zach didn't dare to let down his guard. It seemed that the people were definitely coming to cause trouble.
Luke noticed the badges tied to the shoulders of these individuals in order to discern the ranks of these people. He had long since deduced that these people were soldiers who had arrived to take him away. The most probable reason was because he had interfered with the police and had even killed one of them. Since the police couldn't do anything to him, military force had been deployed to arrest him.
Luke remembered how the tall old warden had previously threatened to retaliate against him through the proper means. Turned out that he had actually done it.