Early Sunday morning residents of Lake Henshaw were woken up by a small tremor of 3.3. Some light shaking was felt across San Diego County. It occurred on the Julian section of the Elsinore fault.

For more info, please read the original article by San Diego Tribune:
http://www.sandiegouniontribune.com/news/science/sd-me-lakehenshaw-quake-20180916-story.html