Boko Haram fighters killed six traders when they ambushed a convoy of lorries under military escort in northeast Nigeria, a civilian militia member and a local resident said on Thursday.
"Six traders were killed in an ambush by Boko Haram gunmen on Tuesday," said Umar Kachalla, from the volunteer security force in Gamboru, a trading hub on Nigeria's border with Cameroon.
The attack happened at about 6:00 pm (1700 GMT) at Mussini village, some 16 kilometres (10 miles) from Gamboru.
Kachalla said the gunmen opened fire on the 23-strong convoy, forcing it to stop, then looted supplies and torched the vehicles.
"The poor state of the road makes it difficult for motorists to escape any ambush because they need to manoeuvre through deep and gaping potholes," he added.
Abubakar Yusuf, from Gamboru, passed the scene on Thursday morning. "I can see the trucks lined up. They are all burnt. Nothing remains but heaps of ash from the goods," he said.
"It is true. Six people were killed in the ambush, including five men and one woman. Attacks against traders have become frequent despite the military escorts."
AFP asked for confirmation and comment from Nigerian Army spokesman Brigadier General Texas Chukwu. In a text message, he said only: "Is not true."
Further questions about whether he meant the attack itself or the numbers involved went unanswered.
Nigeria's government and military maintains that Boko Haram, whose insurgency has killed at least 20,000 people since 2009, is a spent force and on the verge of defeat.
It is now encouraging thousands of people displaced by the conflict to return to their homes from makeshift camps in the Borno state capital, Maiduguri.
But international aid agencies working in the remote region say conditions are not right for mass returns, particularly in terms of security.
Despite claims of free movement, civilian vehicles still require military escorts on roads into and out of Maiduguri because of fears of Boko Haram attacks.
Last weekend, jihadists ambushed troops in the Bama area of Borno and separately overran a military base in neighbouring Yobe.
But the military rejected reports that dozens of troops were killed and told local people "their safety is guaranteed", despite repeated attacks, raids and suicide bombings.
In June, 43 people, including the recently returned displaced, were killed in a wave of suicide attacks in the town of Damboa.