Alleged assault at 4th Street McDonalds with a hammer; what was the beef?

Will update post if EPD has any new information.

From Operation Safe Streets:

Apparently it's HAMMER TIME at 4th Street McDonald's.  EPD and medical are enroute to an assault that just occurred.   Subject was reportedly hit with a hammer in the head.  Suspect ran north from Mcdonalds.

12:04pm - Numerous EPD units on scene.

12:16pm - EPD has one male subject detained.  I'm guessing it's the other end of the altercation.  Subject is uncooperative but detained.

(Updated) 12:23pm units cleared so it's unknown if that was the suspect.