A driver's rear wheels lock up under heavy braking and the back of the vehicle starts sliding sideways. According to the manual, how should the driver correct this drive-wheel skid?

49 CFR 383.111(a)(15); AAMVA CDL Manual (nhcdm.pdf) Section 2.19.2, p. 2-37

A rear-wheel braking skid can quickly turn into a spin-out or, with a trailer attached, a sudden jackknife. Knowing to release the brake first, rather than instinctively pressing harder, is often the only thing that lets the driver regain control before the trailer or rear end swings out of the lane.