Story highlights An ambulance in the convoy treated the boy but could not save him

Ambassador Samantha Power visits the child's family to offer condolences

Trip to Cameroon, Chad and Nigeria is to show U.S. support in Boko Haram fight

(CNN) A top U.S. diplomat has expressed her "great sorrow" after a vehicle in her convoy struck and killed a young boy during an official visit to Cameroon.

Samantha Power, the U.S. ambassador to the United Nations, was traveling to a refugee camp in northern Cameroon when the child was struck Monday, she said hours later in Maroua, capital of the country's Far North Region.

The 8-year-old boy crossed the road without looking near the city of Mokolo, Cameroon's Ministry of Defense said, citing local journalists traveling with the convoy.

U.S. diplomat Samantha Power meets a family who fled Boko Haram.

The ambassador was not in the car that struck the boy, the ministry said.

The child received immediate care from an ambulance traveling with the group but died shortly afterward, Power said.