Two girls said to be aged seven or eight have been used to bomb a market in north-east Nigeria, killing at least one other person and wounding 18.
Police in the town of Maiduguri, Borno state, say the attack happened when the market was crowded with shoppers.
The girls detonated their explosives minutes apart, witnesses said. Both were killed.
No group has said it was behind the bombings but Boko Haram militants have carried out similar attacks.
In the past few months, the Nigerian army has made gains against the group but it still carries out regular bombings.
A member of a militia in Maiduguri, Abdulkarim Jabo, told media the girls were aged about seven or eight and had arrived at the market in a rickshaw.
"They got out of a rickshaw and walked right in front of me without showing the slightest sign of emotion," he said.
"I tried to speak with one of them, in Hausa and in English, but [they] didn't answer. I thought they were looking for their mother."
He said the first girl had headed towards a market stall and then detonated her belt of explosives.
Militants have carried out a string of deadly attacks in north-east Nigeria in recent weeks.
On Friday, a double suicide attack carried out by female bombers killed at least 45 people and wounded 33 at a marketplace in the town of Madagali.
In October, female suicide bombers also killed 17 people at a camp for displaced people in Maiduguri.
- Founded in 2002, initially focused on opposing Western-style education - Boko Haram means "Western education is forbidden" in the Hausa language
- Launched military operations in 2009
- Has killed thousands, mostly in north-eastern Nigeria, and abducted hundreds, including at least 200 schoolgirls
- Joined so-called Islamic State, now calls itself IS's "West African province"
- Seized large area in north-east, where it declared caliphate
- Regional force has retaken most territory since last year