New Delhi, Aug. 29 -- NIAMEY - The gunfire began before sunrise. Residents near Niamey's main airport woke to blasts rattling windows, and by 8 a.m. the government's national television channel had gone dark, replaced by a black screen that persisted across satellite and online platforms for hours.

By mid-morning on Saturday, Niger's defense minister was insisting the situation was under control. Gen. Salifou Mody told the public that a group of soldiers had "broken away from military order" at Base 101, a major military installation on the outskirts of the capital, and had attempted to detain fellow troops. Security forces moved swiftly, he said, and residents should "remain calm and continue their daily activities as usual."

The offic...