From the Wiki page:
Both men faced each other sideways in the dueling position and hesitated briefly. Then Tutt reached for his pistol. Hickok drew his gun and steadied it on his opposite forearm. The two men fired a single shot each at essentially the same time, according to the reports. Tutt missed, but Hickok's bullet struck Tutt in the left side between the fifth and seventh ribs. Tutt called out, "Boys, I'm killed," ran onto the porch of the local courthouse and back to the street, where he collapsed and died.Hickok was later arrested for murder, and tried, but was acquitted on several grounds, not the least that Hickok tried to avoid the duel.
I'm sure that men were shot before that time, but the write-up in the papers made Hickok a household name and this altercation is often cited as the first shootout recorded in the Hollywood tradition of two men meeting in the town square.