Two suicide bombings by militants left a cop along with five civilians dead in Niger a humanitarian worker said.
“The assailants were pursued by inhabitants who told the military and they quickly went after them.”
A municipal official earlier had given a cost of three civilian deaths a city close to the border.
Niger has joined a regional military alliance, alongside Nigeria, Niger and Chad, to fight with Boko Haram, that has been waged a bloody insurgency since 2009 marked village massacres by mass abductions and suicide bombings by girls and adolescents.
Since February the Diffa area has endured several fatal Boko Haram raids.
In June, 38 civilians were killed — including 10 kids — in a Boko Haram strike targeting two hamlets near town.
In July, the prison of the city was raided by the Islamists in a bid that was likely to free detained members .
Boko Haram killed 16 civilians within an assault on a southeastern Niger village precisely the same month.
Diffa lies on the edge with Nigeria that is northeast, where the Islamists have waged a bloody rebellion leaving at least 15,000 dead and two million others homeless.
Tens of thousands have fled to Niger that was southeast to escape Boko Haram with among the biggest refugee camps about 10 kilometres (six miles) .