If the pump fails to prime and/or runs dry, stop the pump. If you're already out of town, call home and have the pump turned off until you return and have an opportunity to fully diagnose the problem.

As you've suggested, it might be a fracture in one of the supply lines, skimmer housing, maindrain or a blockage. You could try to eliminate sources by changing valve to 100% skimmer and, once the pump is on and primed, observe the skimmer throat. If no or very little water is being pulled from the skimmer, you've at least isolated the problem to the skimmer line. Others have found success in dislodging obstructions using a drain king... there are probably threads on this site that describe this in some detail.