Galactic Patrol by E.E. Smith

But Blakeslee, the chief communications officer whose mind and body Kinnison was using, was already armed. Kinnison had seen to that. And as the base commander wrenched open the arms cabinet that happened for which the Lensman had been waiting. Helmuth's private lookout set began to draw current; that potentate himself was now looking on, and the enslaved observer had already begun to trace his beam. Therefore, as the raging commander of Boyssia's pirate base swung about with raised DeLameter he faced one already ablaze; and in a matter of seconds there was only a charred and smoking heap where the commander had stood.

Kinnison wondered that Helmuth's cold voice was not already snapping from the speaker, but he was soon to discover the reason for that silence. Unobserved by the Lensman, one of the observers had recovered sufficiently from his shocked amazement to turn in a riot alarm to the guard room. Five armed men answered that call on the double, stopped and glanced around.