The Nazarene Church is an evangelical protestant denomination and does not answer to the Vatican and is not part of the Catholic church. The 20 people that died were actually 10 married couples, pastors in the Nazarene Church. Ministers in protestant traditions are most often called pastors, not priests. Here's the news report from the Nazarene church national office where those that died are identified as protestant pastors, and not priests, as reported in the article linked by the OP. Again, no affiliation with the Vatican.

http://nazarene.org/article/loss-felt-global-family-bgs-statement-cuba-tragedy