Of the 154 shooters, four women either helped to commit or committed a shooting themselves. The most recent case is Nasim Aghdam who shot three people at the YouTube headquarters in San Bruno, California on April 3. The other 150 shooters were men.
There are nine states in which there have not been a mass shooting.
This information was compiled from the following sources: "The terrible numbers that grow with each mass shooting," March, 2018, The Washington Post; "The latest: YouTube shooter bought pistol in January," April, 2018, The Washington Post.