New Delhi, July 23 -- ABUJA - In the village of Sauna in Zamfara State on Wednesday, a large group of armed bandits descended on communities in the northwest Nigerian state between the hours of three and four in the afternoon, targeting, in the words of the local district representative, "all the people they meet." At least 20 people were killed. The attack was among the deadliest single incidents in a region that has endured years of relentless gang violence, and it came less than two weeks after President Bola Tinubu's government celebrated the rescue of 46 kidnapped schoolchildren from southern Nigeria as evidence his security strategy was working.

Nasiru Lauwali, who represents the Sauna district, said the scale of the attack was mar...