This does not refer to sundown. Rather, the light of the sun turned dark during the middle of the day. Use a term to describe the sun becoming dark rather than the sun going down.
"the curtain of the temple was torn into two pieces." This can be stated in active form. Alternate translation: "God tore the temple curtain into two pieces" (See: [[rc://en/ta/man/translate/figs-activepassive]])