Exactly that, probably WSR (not confirmed), but apparently spoke Taiwanese/Hokkien to the congregation to get himself in, so maybe WSR from Fujian?
Again, really don't trust the Discourse on Twitter to be sane about talking through this.
According to US-based TVBS reporter Ni Chia-hui, the shooter is confirmed to have been born in Taiwan
https://facebook.com/nichiahui/posts/544605013904005…