Gunmen killed at least ten United Nations peacekeepers from Chad in an attack on a base in Aguelhok in northern Mali, the U.N. said.

In a statement, MINUSMA said that peacekeepers in Aguelhok, around 120 km (75 miles) north of Kidal towards the border with Algeria, “repelled a complex attack by attackers arriving on board many armed vehicles” early on Sunday, January 20.

Eight peacekeepers had so far been confirmed dead and several others were wounded, MINUSMA said.

Stéphane Dujarric, the spokesperson for the U.N. Secretary-General Antonio Guterres said in a later statement that 10 peacekeepers from Chad were killed and at least 25 injured.

Blue helmets “neutralized many enemies” and pursued the assailants, the MINUSMA statement said, adding that air operations were being conducted in the area.

“Peacekeepers of the MINUSMA force at Aguelhok fought off a sophisticated attack by assailants who arrived on several armed vehicles,” Mahamat Saleh Annadif, the U.N.’s special representative for Mali said in the statement.

“It demands a robust, immediate and concerted response from all forces to destroy the peril of terrorism in the Sahel,” he added.

A Malian security source earlier spoke of at least six killed and 19 wounded, while a diplomat in northern Mali told AFP that several of the attackers were also killed.

The Menastream risk consultancy tweeted that seven peacekeepers were severely injured, while three militants were killed an one was captured.

Al-Qaeda in the Islamic Maghreb claimed responsibility for the attack, saying it was “in reaction” to the visit to Chad by Israeli Prime Minister Benjamin Netanyahu, according to the Mauritanian Al-Akhbar news agency, which regularly receives statements from the group, AFP reported.

France 24 analyst Wassim Nasr tweeted screenshots of a statement from the Support Group for Islam and Muslims (JNIM) claiming the attack. JNIM is Al-Qaeda’s branch in Mali, and was formed in 2017 by the merger of several smaller groups including the Sahara branch of AQIM, Ansar Dine and Al-Mourabitoun. Its leadership has pledged allegiance to Al-Qaeda leader Ayman al-Zawahiri.

The statement said the attack was in accordance with Zawahiri’s call to prevent “normalization” of ties with Israel.

Last April, two Chadian U.N. peacekeepers were killed and 10 others wounded in an attack on the same base in Aguelhok.

The recent unrest in the Sahel began in Mali in 2012 with Tuareg separatist uprising against the state, which was exploited by Islamist extremists linked to al-Qaeda who took key cities in the desert north.

France began its Operation Serval military intervention in its former colony early the next year, driving the jihadists from the towns, but the militant groups morphed into more nimble formations operating in rural areas, sometimes winning over local populations by providing basic services and protection from bandits.

The insurgency has gradually spread to central and southern regions of Mali, and across the borders into neighboring Burkina Faso and Niger.

Large swathes of the country remain outside government control, despite a 2015 peace accord designed to isolate the Islamists.

The French mission evolved into the current Operation Barkhane, which has roughly 4,500 French personnel deployed with a mandate for counter-terrorism operations across the region.

Troops deployed to Barkhane work alongside the U.N. Minusma stabilization mission in Mali, which began in 2013 and has about 12,000 troops and 1,750 police deployed, as well as the G5 Sahel joint counter-terrorism force that aims to train and deploy up to 5,000 personnel.

With reporting from AFP. This post was updated several times on January 20. The distance between Kidal and Aguelhok was corrected on April 3