“Six people died, including a soldier,” in the attack in Kaiga-Kindjiria district, said the source, speaking on condition of anonymity.
A number of people were also injured, the officer said, without giving figures.
A provincial security official said a woman wearing an explosives-laden belt “blew herself up near the home of a traditional chief”.
Four guards as well as a soldier were among the dead, and five people were wounded, the official said.
The death toll of six was confirmed by Chadian army spokesman Colonel Azem Bermandoa, and by a local NGO.
There was no immediate claim of responsibility.
Kaiga-Kindjiria lies in Lac province, which abuts the vast Lake Chad — a region shared by Chad, Cameroon, Niger and Nigeria.
Boko Haram launched an insurgency in northeastern Nigeria a decade ago, that has since spilled over into neighboring countries.
It has carried out at least 10 cross-border attacks in Chad since 2018, mainly targeting army positions.
In March, 23 troops were killed when their forward position on the northeastern side of the lake came under attack.
In June, 11 soldiers were killed and six were wounded in clashes at Tchoukoutalia, according to the authorities, who said 26 jihadists were killed.
Boko Haram’s campaign has left some 27,000 people dead and displaced around two million in Nigeria alone, according to some estimates.
In 2015, the four Lake Chad countries, together with Benin, set up a combined force to fight Boko Haram with the help of local groups of armed citizens.