The union could be listed as a defendant along with the city and some individual union members and leaders. Getting class action status is a different matter. Family members related to the dead would probably have standing to sue for wrongful death as individuals.
Basically, anybody can sue for anything, but it’s hard to sue successfully in such situations because the plaintiff has to prove that the negligent behavior was the proximate cause of death. It’s all about medical experts.
What would be sweet would be to get fat judgments against the union members who did this and garnish their wages for years to come. THAT would put a quick stop to such a thing happening anywhere again.
....oops....not proximate cause. Contributory negligence.