Several hundred million years after the Big Bang, the very first stars flared into the universe as massively bright accumulations of hydrogen and helium gas. Within the cores of these first stars, extreme, thermonuclear reactions forged the first heavier elements, including carbon, iron, and zinc.
source https://www.lifetechnology.com/blogs/life-technology-news-blog/explosions-of-universes-first-stars-spewed-powerful-jets