Unbeknownst to the group, Medusa was right in the sense that the explosion that took place in the lost city of San Antonio didn't go unnoticed. Authorities from Hollywood city in the west were trying to gather as much information as they could thanks to the hunters whose traits allowed to surpass the limits of human senses, but those who could see far in the distance didn't have night vision and those who did have night vision lacked the ability to see from afar.
There were some hunters with extra sensory perception, but it was also limited and didn't work well at such distance. At least not as well as Sam's lightbringer trait which allowed him to see as far and wide as he wished, his only limitation being physical objects.