Notice the overall dark look to the back of these birds, with Short-bills having broader orange/rufous edges, giving the back a different look. The lighter-marked bird to the left had me wondering for a minute about Short-billed, but everything added up to Long-billed with it. Notice the wingtip falling short of the tail, and the long tibia on all these birds.

This group flew around the pool a couple of times, with nothing but 'keeks' to be heard.