Though heavy civilian casualties are routine in the military’s confrontation with Boko Haram, with dozens dying in poor neighborhoods since 2010 as the army searches for “suspects,” Nigeria’s politicians usually have little to say about them. Past massacres of civilians in retaliation for soldier deaths have passed largely with impunity.

This time, there have been calls in Nigeria’s national assembly for an investigation, and the government has come under harsh criticism at home and abroad, including the United States. The military has said it has begun its own inquiry, and some longstanding observers of the country’s heavy-handed fight against Islamist militants say a tipping point may have been reached.

“This is coming at a time when we have had similar situations” elsewhere, said Kole Shettima, chairman of the Center for Democracy and Development in the capital, Abuja. “People are tired of the excuses the military is giving, and that’s why they are demanding an investigation. This time it’s different. There is a crisis of legitimacy in the military.”

But in a country where corruption abounds and accountability is rare, others wondered whether it would truly become a watershed moment — or get brushed aside as an unfortunate side effect of fighting a dangerous insurgency.

“This Baga is just on a bigger scale, but they have been doing this for ages,” the governor of Borno State, Kashim Shettima, one of the first officials to reach Baga afterward, said of the military. “They’ve not adhered to the rules of engagement,” said Mr. Shettima, who is not related to the democracy advocate. “When you burn down shops and massacre civilians, you are pushing them to join the camp of Boko Haram.”