Without a word of warning

It seemed as though no one else noticed the policeman walk in, but Rock, from his desk in the newsroom, watched as he entered through the front door. He was short and stocky, with dark hair and a bushy mustache, and dressed in a standard navy-blue cop outfit.
The cop walked to Rock's desk, drew his pistol and looked over the side of an adjacent cubical. He took aim at someone or something Rock couldn't see, hesitated for a second, and without a word or warning fired two shots. He then held the gun at his side as he whispered something into a radio. Rock was frightened, but he noticed that the woman seated beside him had continued a phone interview throughout the incident without so much as a glance away from her desk, and it seemed as if her take was typical of everyone else's in the office.