An Arizona driver allegedly gunned down another motorist — for simply looking at him while stopped at a red light, authorities said.

Nicholas Elliott, 26, was arrested Thursday in connection with the March 1 road rage incident that killed Alex Mixon, also 26, in Phoenix, local police said.

Authorities initially believed that Mixon died in a car accident, in which his car clipped a utility pole and smashed into a wall near Thunderbird Road and 30th Street, police said in a statement.

But as authorities investigated, they discovered that Mixon had been shot — apparently for glancing over at Elliott — who allegedly bolted from the scene.

Court documents obtained by the Arizona Republic reveal that an anonymous person reported overhearing Elliott talking about shooting someone in the face because the man gave him a dirty look as they stopped next to each other at an intersection.

Other witnesses reported that Elliott had bragged about the shooting.

When interviewed by police, Elliott claimed he remembered arguing with a man at a red light but did not recall whether he had fired a weapon, according to the documents.

He also said that “if he could go back in time, he would take the incident back,” the court documents said.

Drugs and firearms were recovered during Elliott’s arrest, and he acknowledged that they were his, the documents stated.

He was ordered held on $1 million bond and his next court appearance is scheduled for Thursday, the paper reported.