Or perhaps leftists fired shots as a warning, or perhaps the shots came from "pro-business" conservatives who lose the opportunity to exploit cheap labor (the assault came a day after the big raid in businesses employing hundreds of illegal workers), or perhaps the shots were fired by Trump supporters just to change the narrative. You do not know!
Still, the big picture is clear.
Since 1970s, more police officers have been killed by right-wing violence than left wing
https://www.adl.org/media/10827/download
Page 12 is clear
Notice also that the majority of police officers killed by the left-wing is in the past (before 1980 ) while the majority of police officer killings by right-wing is after 1990.