Believe it or not, the FBI actually doesn't classify the murder of two people as a mass shooting. Which is why she an the other women you thought of may not have come up in my research. They may have been classified as "spree killings." (NOT a consolation to the surviving relatives, no matter how they are classified.)
"The FBI defines mass shootings as “Four or more murders occurring during the same incident, with no distinctive time period between the murders. These events typically involve a single location, where the killer murdered a number of victims in an ongoing incident.” There may or may not be additional persons injured in such events."