Assassins.

Valerian's shout alerted all the people, the guards followed his gaze and they saw a man standing amidst the crowd with a bow and arrow in his hands. This man was slightly startled by the shout, but he did not miss his aim and let loose the arrow on his string. 

The people had yet to react when the arrow flew through the void and headed towards the emperor. The rest of the people were still in a daze, fortunately, Valerian acted, as he said, "Ventus Scutum." 

A strong gust circulated the carriage, catching the arrow in its flow. However, this was not the end, the crowd was agitated and they were all screaming and yelling in panic. The assassin saw that his first attempt has failed so he knocked another arrow but Valerian was fast and said, "Micare." 

A small flash of light left the man with impaired vision. Vertex gazed at the man and said, "Kill him."