Four people have been arrested after a deadly stabbing that left several police officers injured in eastern France that authorities linked to Islamic extremism.

As he began his attack, the 37-year-old was heard shouting, “Allahu akbar,” according to France’s antiterrorism police. The Arabic phrase, meaning “God is great,” is an everyday expression used in religious and nonreligious settings alike, but has also become a war cry in some terrorist attacks by Islamic fundamentalists.

One person has died and several are wounded following a knife attack at a town market in eastern France, in what French authorities have described as an act of terror.