Boarding three boats, militants crossed Lake Chad Friday morning and attacked the nearby Ngouboua village, killing at least ten people including the village’s top dignitary, eyewitnesses told The Anadolu Agency.

A senior Chadian military official has confirmed the attack but declined to provide a death toll.

The official, who requested anonymity, said that Chadian army forces have started chasing down Boko Haram militants following the attack.

Friday’s attack was the first by Boko Haram in Chad, coming on the heels of Chadian military participation in a campaign against the militant group at the Cameroonian-Nigerian border.

The campaign, which kicked off last month, came after Chadian President Idriss Deby vowed to confront Boko Haram militants in areas close to Chad Lake.

For the last six years, Nigeria has battled a fierce Boko Haram insurgency that has ravaged the country’s volatile northeast and claimed thousands of lives.

In recent months, Boko Haram has graduated from simple guerrilla tactics to capturing entire towns in Nigeria’s Adamawa, Yobe and Borno states, where the group has declared a self-styled “Islamic caliphate.”

Since the beginning of 2015, Boko Haram has also stepped up attacks in neighboring countries.