Multiple Indicies with limit

Quick question. When a query is run on multiple indexes with a limit, does elasticsearch query all indexes simultaneously (and return only the given limit number of results)? Or does elasticsearch query the first index for the limit and then proceed to the next if not enough results are returned. I believe it is the former, but I cannot find the reference.

You mean https://www.elastic.co/guide/en/elasticsearch/reference/2.4/query-dsl-limit-query.html?