SAN JUAN, Puerto Rico—Federal authorities detained 17 Dominican migrants on Friday after their boat capsized near Puerto Rico’s northwest coast in the pre-dawn hours, with the U.S. Coast Guard searching for an estimated 10 others still missing. Jeffrey Quiñones, a Customs and Border Patrol spokesman, told The Associated Press that those detained told officials that a total of 27 people were aboard the boat that struck a rock and turned over near Shacks Beach in Isabela. “There are no indications that they have drowned,” he said of those still missing. The boat, known as a yola, overturned about 75 yards (69 meters) from shore, U.S. Coast Guard spokesman Ricardo Castrodad told the AP. He said authorities received a 911 call from somebody who heard the migrants splashing and running. No migrants were rescued at sea, although he said the Coast Guard searched for several hours. The incident comes a day …