After a trail run with activity 'stopped', I accidently triggered the Incident Detection ("ID"). The issue, however, is that I could not cancel it. After ID was triggered I received the ID screen with countdown to cancel.  It was quickly followed by a separate notification (much like a text notification) screen indicating an ID event. When I cleared that notification, the screen switched back to the ID countdown, decreased by 1, immediately followed by another ID notification text.

This loop continued over and over reducing the ID countdown (10..9..8..7..), and there was no way to cancel the ID. I finally had to power down the watch by holding the Light button
When it powered back up, I was returned to the run activity screen and it made a sound as if just stopped. A few hours later, I opened my iPhone and switched to Garmin Connect app. It too was stuck in never ending notification ID event with cancel button. Hitting cancel would just reveal another notification.  Required me to close the app and re-open.

Steps followed:

1. 'Start-Stop' button --> Trail Run activity --> 'Start-Stop' button
2. 7 mile run --> 'Start-Stop' button
3. Walked to car where phone was
4. Removed shoes and banged them together to shake the dirt off
5. ID triggered and could not be canceled