[en] We present numerical evidence that the SU(4) pure-gauge dynamics has a finite-temperature first-order phase transition. For a 6 x 20³ lattice, this transition occurs at the inverse-square coupling of 8/g² ∼ 10.79. Below this and above the known bulk phase transition at 8/g² ∼ 10.2 is a confined phase in which we find two different string tensions, one between the fundamental 4 and 4* representations and the other between the self-dual diquark 6 representations. The ratio of these two is about 1.5. The correlation in the adjoint representation suggests no string forms between adjoint charges