Alaska ? A sightseeing airplane crashed near Ketchikan, an island city in southeast Alaska, killing five people, including a 3-year-old boy, his parents and his grandfather, authorities said.

Four people survived the crash Thursday, including the boy’s grandmother and twin sister, who was in critical condition in a Seattle hospital, officials and neighbors of the Oregon family said.

Ketchikan Public Safety Director Rich Leipfert said the SeaWind Aviation plane crashed into a tree at Traitors Cove, about 25 miles north of Ketchikan. The cause was under investigation.