Some 1,000 suspected Boko Haram fighters from Nigeria attacked five towns in northern Cameroon over the weekend and briefly occupied a military camp on Sunday before being dislodged by the air force, an army spokesman said.

The heavily armed group attacked the military camp in Achigachia near the Nigerian border at around 4 a.m.. Following an intense battle, the army abandoned the camp, Lt. Col. Didier Badjeck told Reuters by phone.

“After that, the head of state ordered the air force to carry out strikes. With the bombardment, the fighters were forced to decamp from Achigachia,” Badjeck said.

He could not immediately give the number of casualties from both sides. It is the first time Cameroon has used the air force against Boko Haram.

Islamist Boko Haram, which is fighting to create a caliphate in northern Nigeria, has stepped up attacks on both sides of the border, prompting Cameroon to send thousands of soldiers to the region to stop the militants.

Cameroon state radio CRTV said the militants carried out attacks on five towns over the weekend and at least one Cameroonian soldier was killed.

“The attacks were carried out simultaneously at the localities of Mokolo, Guirvidig, Waza, Amchide and Makari, villages along the frontier with Nigeria,” CRTV radio reported.

Boko Haram has made several incursions in the Far-North Region of Cameroon this year, killing over 40 soldiers and recruiting hundreds from mainly unemployed youths in the area.

The Cameroon army said last week it dismantled a training camp for the militants in northern Cameroon, arresting or killing dozens and seizing 84 children who were being trained there.