Per p. 23 of the July 6, 1924 New York Times:
[It] happened in the fourth inning, when Babe made a valiant effort for a long foul from Joe Judge’s bat, which just sailed over the wall into the crowded seats. The Babe ran into the pavilion parapet with the full force of his body, and dropped unconscious to the grass. Uniformed policemen ran to his assistance and kept back the crowd that seemed disposed to leave the chairs and get a close-up of the injured warrior. Several photographers happened to be on the spot and snapped the Babe as Trainer Doc Woods ran up with the water bucket and the little black bag of first aid preparations.
At first it was thought that Ruth had been knocked out by a blow from the concrete on his chin, but it was soon discovered that he had been knocked out by a jolt in the solar plexus. His left leg was also hurt at the hip.
[Yankee manager Miller] Huggins wanted Ruth to quit, but he insisted upon staying in, and got a double in the sixth…