Police in Phoenix are now investigating up to six more suspected cases of shots being fired at vehicles on Interstate 10, in addition to the 10 previously reported incidents since Aug. 29.

Investigators says it's still unclear if the shootings, which they called "domestic terrorism," are related or if there might be multiple shooters.

Jonathan Hunt told Shepard Smith this afternoon that authorities have confirmed that at least one of the five new incidents was a shooting, but they won't say more than that the others were "projectiles" striking vehicles.

"In this situation, which is increasingly dangerous, cops say they are obviously doing every single thing they can to find out who is doing this," Hunt said.

A $20,000 reward is being offered for information leading to an arrest.

Watch the clip above.