"You can find somebody else to do it because I will not." -Arnold on shutting down the system.
"John, they are out there where people are dying." -Ellie indicating that more people are out there dying.
"Call the mainland. Tell them to send the damn helicopters" -Grant indicating that more than one chopper would be needed to evacuate.
It doesn't directly state that there are others on the island, but it does leave that open quite nicely.
Also, I doubt the entire staff of such a large island would all fit on one small supply ship. I think only non-essential personnel left. I'm certain that park security, some maintenance, and animal control would still be on the island to maintain it over the weekend. The park can only run on minimum staff for up to 3 days but it's not stated exactly how many people minimum staff is.