The website deliberately changes the definition of "mass shooting" to inflate the number. This is intellectually dishonest.
I went over the list. There is only 1 mass shooting.
According to FBI:
The United States' Congressional Research Service acknowledges that there is not a broadly accepted definition, and defines a "public mass shooting" as one in which four or more people selected indiscriminately, not including the perpetrator, are killed, echoing the FBI definition of the term "mass murder".