Syrian refugees in greece

Yesterday, a friend of mine flew to lesvos (or lesbos, as it's also called) to help the refugees. She's with three others who are part of a group known as clowns without borders. She's been to Haiti and other places that have been dealing with weather related disasters, but never to a place with people fleeing from war. There aim is to provide some light entertainment to kids and families who need laughter as much as they need medicine.
Unfortunately, they will also be pulling dead bodies from the sea and other tasks that they haven't had to do before. CWB pays her air fare and some is providing a house for them to stay. She will return a different person. I'm sure she'll need counseling for a while when she comes stateside again.
These refugees live. In a landlocked country. Most have never seen a large body of water, let alone an ocean. They don't know how to swim and those that survive are then faced with a 43 mile trek to register as refugees in Greece.
Given the recent unsavory political climate favored by that carnival barker Trump, and the fact that over 900 deaths have been caused by Americans shooting each other this year alone, is it realistic to be afraid that one of these refugees might be a terrorist?