Free Orphans of the Sky by Robert A. Heinlein

shouted, "Hold your breaths! Mind the gas!" The radioactive vapor poured lazily out from the broken tube above and filled the crossing with a greenish mist.
           Hugh ran to the right, thankful for his knowledge as an engineer of the lighting circuits. He had picked the right direction; the passage ahead was black, being serviced from beyond the break. He could hear footsteps around him; whether they were friend or enemy he did not know.
           They burst into light. No one was in sight but a scared and harmless peasant who scurried away at an unlikely pace. They took a quick muster. All were present, but Bobo was making heavy going of it.
           Joe looked at him. "He sniffed the gas, I think. Pound his back."
           Pig did so with a will. Bobo belched deeply, was suddenly sick, then grinned.
           "He'll do," decided Joe.
           The slight delay had enabled one at least to catch up with them. He came plunging out of the dark, unaware of, or careless of, the strength against him. Alan knocked Pig's arm down, as he raised it to throw.
           "Let me at 'im!" he demanded. "He's mine!"  
           It was Tyler.  
           "Man-fight?" Alan challenged, thumb on his blade.  
           Tyler's eyes darted from adversary to adversary and accepted the invitation to individual duel by lunging at Alan. The quarters were too cramped for throwing; they closed, each achieving his grab in parry, fist to wrist.
           Alan was stockier, probably stronger; Tyler was slippery. He attempted to give Alan a knee to the crotch. Alan evaded it, stamped on Tyler's planted foot. They went down. There was a crunching crack.
           A moment later, Alan was wiping his knife against his thigh. "Let's get goin'," he complained. "I'm scared."
           They reached a stairway, and raced up it, Long Arm and Pig ahead to fan out on each level and cover their flanks, and the third of the three choppers—Hugh heard him called Squatty—covering the rear. The others bunched in between.
           Hugh thought they had won free, when he heard shouts and the clatter of a thrown knife just above him. He reached the level above in time to be cut not deeply but jaggedly by a ricocheted blade.
           Three men were down. Long Arm had a blade sticking in the fleshy part of his upper arm, but it did not seem to bother him. His slingshot was still spinning. Pig was scrambling after a thrown knife, his own armament exhausted. But there were signs of his work; one man was down on one knee some twenty feet away. He was bleeding from a knife wound in the thigh.
           As the figure steadied himself with one hand against the bulkhead and reached toward an empty belt with the other, Hugh recognized him.
           Bill Ertz.
           He had led a party up another way and flanked them, to his own ruin. Bobo crowded behind Hugh and got his mighty arm free for the cast. Hugh caught at it. "Easy, Bobo," he directed. "In the stomach, and easy."
           The dwarf looked puzzled, but did as he was told. Ertz folded over at the middle and slid to the deck.
           "Well placed," said Jim.
           "Bring him along, Bobo," directed Hugh, "and stay in the middle." He ran his eye over their party, now huddled at the top of that flight of stairs. "All right, gang—up we go again! Watch it."
           Long Arm and Pig swarmed up the next flight, the others disposing themselves as usual. Joe looked annoyed. In some fashion—a fashion by no means clear at the moment—he had been eased out as leader of this gang— his gang—and Hugh was giving orders. He reflected that there was no time now to make a fuss. It might get them all killed.
           Jim did not appear to mind. In fact, he seemed to be enjoying himself.
           They put ten more levels behind them with no organized opposition. Hugh directed them not to kill peasants unnecessarily.