That is what some witnesses said that they thought it sounded like. How many actually said that they saw another rifle (other than the one in the TSBD sixth floor window)?
The people in DP were there to see JFK & Jackie.
They were watching the Limo as it came/went down Elm.
Their eyes weren't focused on other areas of the Plaza.
The best that can be expected is what we got.
However there are witnesses who saw bullets hit in spots other than the Limo.