Abuja, Nigeria—— Over the years, Nigeria's military has accidentally killed hundreds of civilians in airstrikes targeting armed groups in the country's conflict-torn north, many of whom were bombed in their own villages.

The latest fire incident occurred on Saturday when the Nigerian air force bombed rebels in the conflict-torn northwestern state of Zamfara but ended up accidentally killing civilians working with community security agencies, the state government said. Residents told The Associated Press that at least 20 civilians died.

The military has killed about 400 civilians since 2017, according to SBM Intelligence, a Lagos-based research firm that collects reports and data on airstrikes from affected villages.

Rights groups and citizens have expressed concern about the military's actions in Africa's most populous country, which has been grappling with a violent security crisis on multiple fronts for years.

Nigeria's Defense Minister, Gen. Christopher Musa, said the military has been improving its human rights record and is holding its personnel accountable.

In addition to the Boko Haram Islamic extremist group, which launched an insurgency in 2009 to assert its radical interpretation of Islamic law, known as sharia, dozens of armed groups exist in the northeast.

They are mostly former pastoralists locked in a decades-long conflict with farming communities over land and water rights. Once armed with clubs, these groups now use guns smuggled into the country to carry out attacks, killing around thousands of people each year.

Armed groups carry out mass killings and kidnappings for ransom in the northwest and central regions. They also extort tax revenue from the communities they terrorize, using the funds to support their operations in addition to paying ransoms, analysts say.

The armed groups operate in vast forest enclaves, planning and launching attacks, sometimes lasting for days in villages with inadequate security. They rarely stay in one location for long, often relocating and blending into local communities to evade detection.

As a result, the Nigerian military often relies on air strikes to target rebel activities and hideouts, especially in areas where ground attacks are difficult.

Authorities say avoiding civilian casualties in airstrikes can be challenging because armed groups often use civilians as human shields.

"Bandits and terrorists, unlike professional soldiers, do not abide by the rules of engagement. They do not care about killing hostages if they are attacked," former Nigerian President Muhammadu Buhari once said.

However, Abuja security analyst Senator Irogbu said frequent errors leading to civilian deaths could also be attributed to gaps in intelligence collection and insufficient coordination between ground forces, air assets and stakeholders.

Nigeria's government and military have frequently pledged to investigate accidental airstrikes to prevent their recurrence. Yet analysts say the problem persists and such investigations often go nowhere.

In 2024, the Nigerian military took the rare step of prosecuting two individuals for launching an accidental airstrike in Kaduna state that killed more than 80 civilians. It also promised to release an investigation report into the incident, but has yet to do so.

A key step is increased investment in pilot training and crew development as well as upgrading aircraft and targeting systems," said Oluwole Ojiwale of the Africa-focused Security Institute.

He said the military also needed to build trust and secure support from local communities, whose intelligence on the activities of armed groups was crucial to accurately targeting and defeating them.