Grimm looked around and noticed the very visible amount of increase in the quantity of bystanders. Perhaps other fancied similar pleasures as he did? Probably just the human tendency to run towards what could possibly be hazardous. He noticed the terrorist seemed to have a similar expression as him, unfamiliar with the authorities methods. The man spoke to the woman about the explosives wrapped around him, threatening to blow himself up. Grimm just leaned on the nearest tree and held his head low while swinging his head left and right every time he heard something he disapproved. 
[i]Humans.....[/i]
He wouldn't mind running up to him and pressing the detonator himself, this man was an annoyance to him. 
The skeletal boy looked up when the terrorist aimed his rifle at Sayaka.... [i]Could at least wait for her to show you what she has prepared for you....[/i] Grimm laughed a bit despite the lack of anything perceivably funny. Grimm pushed the statement made in his head aside and started to stride toward the man about to shoot someone, but before he could do anything a man jumped between the terrorist and detective; cutting through the mans rifle easily. Grimm's ordinary standard sword couldn't perform such a task, this man or sword was different. No surprise in Utopia but Grimm found it interesting. Everyone had their guns aimed towards the heroic swordsman. The man received another and made demands about some grand monetary gain of a sort. The heroic man's sword clearly was magical when something odd spiraled around it. 
Grimm looked on curiously but a sniper had shot right through his blade. If now wasn't the time to attack then when?

When a few are immobilized is when. Grimm began to run towards one of the terrorists smirking, his hand on his ordinary knife. One of the terrorists unfrozen by the police probably pissed his pants when Grimm grabbed him from behind. He unsheathed his blade while having his other hand covering the terrorist's mouth. 
"Shhhhhh." He laughed a bit while telling him to shut up. As if his uncomforting shhhh's would make him quiet. Grimm gradually took his blade out, savoring every single moment, running his fingers along the hilt constantly until the blade touched the fallen man's throat. "Farewell." He said casually as if saying good bye to an old friend he had just run into on accident. In less than a second the blade was no longer touching his neck, but being wiped on Grimm's shirt. This would be the only epitaph for the bastard. 
Grimm ran to the next terrorist closest to him and let his blade enter his abdomen. The smirk on his face not truly depicting his content. This grandeur display was beautiful in every aspect. Grimm proceeded to butcher as many terrorists as possible.
[i]Shit... I forgot to count.[/i]
He removed the explosives from one of the terrorists and held onto it. Only one hand needed to entertain himself with all the childish beings around him.
He would never get bored of these toys. After sometime, he grabbed one of their rifles and looked around. He had forgotten [b]waaaayyy[/b] too many of them. He aimed the rifle he was incredibly untrained with at a terrorist and used the weapon properly.
He then turned and looked for the sniper. He would have to wait for the next shot fired by him/her to find them. He then proceeded to actually look where the blood splattered, his general location could be found that way if he didn't move around. Grimm continued to analyze the area around him.