COX’S BAZAR, Bangladesh — Hours before ex-Bangladesh Prime Minister Sheikh Hasina fled the country in the face of a student-led uprising, Mohammad Sabur and his family were escaping civil war in neighboring Myanmar.

Caught in fierce fighting between rebels and government troops, the family of Rohingya tried to cross a river and toward the relative safety of Bangladesh. But all five of Sabur’s children drowned after their boat capsized, the youngest victim just three and a half.