Good Guys by Steven Brust
Donovan was shot by a cop. For jaywalking, supposedly. Actually, for arguing with a cop while black. Four of the nine shots were lethal - or would have been, if their target had been anybody else. The Foundation picked him up, brought him back, and trained him. Lethal turns out to be a relative term when magic is involved. When Marci was fifteen, she levitated a paperweight and threw it at a guy she didn't like. The Foundation scooped her up for training too. Hippie chick Susan got well into her Foundation training before they told her about the magic, but she's as powerful as Donovan and Marci now. They can teleport themselves thousands of miles, conjure shields that will stop bullets, and read information from the remnants of spells cast by others days before. They all work for the secretive Foundation... for minimum wage. Which is okay, because the Foundation are the good guys. Aren't they?