Most of the population left the island by boat. Fortunately, the lava flows and tephra fall did not at first affect the island's airstrip (Vestmannaeyjar Airport), and a few people who were unable to travel by boat were evacuated by air—primarily the elderly and patients from the hospital. Planes were sent from Reykjavík and Keflavik to help speed the process. Within six hours of the onset of the eruption, almost all of the 5,300 people of the island were safely on the mainland. A few people remained to carry out essential functions and to salvage belongings from threatened houses. Cattle, horses and sheep on the island were slaughtered. On the mainland, friends, relatives and strangers offered shelter and housing. By the end of the day, all 5,300 people were spread around cities and towns on the mainland.