My Lai wasn’t the only such massacre conducted in the Vietnam War by US troops. There were many more, but the number of killed in each incident was typically fewer. Numbers were often 10-20, but ranged from five to 30 all the way up to 100. Most took place between 1966-1968.
In fact, there were 19 Allied massacres in My Lai’s province alone in the first three months of 1968. A number of them were conducted by ROK South Korean troops.