18:22: Reporter: "So, Chief Best, you stood here on Friday and you said it was going to be your decision and your decision alone to use tear gas. Tear gas was deployed on Sunday. You released a video today to say that it was not your decision to close the East Precinct. So who is making tactical decisions right now, for the Seattle Police Department?"
18:51: Best: "So for the tear gas, it was my decision. ... We suspended the use for 30 days unless it was a 'life safety situation.' And that was the exemption. ... The officers felt like it was a 'life safety situation' ... and I concurred."
19:27: Best: "I own that decision. I made that decision."
Here's a press conference transcript from June 7 where they claimed they would stop using CS gas[2].
Here's a secondary source reporting on the June 11 press conference[3].
[1]: https://www.youtube.com/watch?v=_rE4VMjClqI
[2]: https://durkan.seattle.gov/2020/06/transcript-mayor-durkans-...
[3]: https://www.thestranger.com/slog/2020/06/11/43893335/durkan-...