ATS is a news agency name (full name is Keystone ATS). So in this case it seems to be a source name, not author.
Type of issue
Author added their own content
Reported
Mar 3, 2019
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You can see on the next page where the author is explicitly listed, but there is also this abbreviation
https://www.arcinfo.ch/articles/suisse/crans-montana-vs-avalanche-sur-les-pistes-4-blesses-dont-un-pronostic-vital-engage-les-recherches-continuent-821422
I couldn't find a writer like that
https://www.arcinfo.ch/auteurs/ats/