Two or Three Neutron Stars ???

Well so far I have not read in books or heard anyone in this group say
neutron stars are sci-fiction. We know they are out there,and their
usually seen as a binary system rotating very fast around each other.
Someday we will see this system having three neutron stars(tri-system)
It makes some sense to me with the strong mutual gravity attraction
these two neutron stars should move closer,and closer,and we should be
able to measure this shrinking distance. That means in time they will
collide. This scenario begs three questions. What happens when they slam
together? Will it be a blast of gamma photons? Will they just disappear
because their greater density created a single black hole? Well I say
it would take three neutron stars to create a single black hole. Bert