Alan Grant, Ellie Sattler and Donald Gennaro had followed the Velociraptors onto the beach after exiting from the nest while inspecting the number of eggs. Grant realized that the animals wished to migrate, mere seconds before they were all scattered by the sudden noise of several Costa Rican military helicopters appearing through the fog. One of the helicopters had already picked up Robert Muldoon as well as Tim and Lex Murphy, as well as transported a number of Costa Rican soldiers. The Helicopter was large enough enough to fit the eight survivors, as Grant, Ellie, and Gennaro boarded the same helicopter as Muldoon and the kids to escape the island. It was also large enough for at least two Costa Rican soldiers to fit in as well. The door of the helicopter was left open so that Grant was able to witness the destruction of Isla Nublar.
The make and model of the Helicopters are currently unknown as the total number of them,however there were at least two mentioned. They were operated by the Costa Rican National Guard. The helicopters had also evacuated Gerry Harding and the rest of the surviving workers in the Island. The Helicopters that remained behind as the rescue chopper left commenced promptly on the fire-bombing of Isla Nublar, to destroy all the animal life on the island. They bombed the island repeatedly with Napalm, until the island seemed to be ‘glowing’ from the heat of the bombs.
Jurassic Park by Michael Crichton page 395-397 (First Edition, Thirty Fourth printing)