A female Isis fighter used three young children as a decoy to approach Libyan forces before blowing herself up.
Several women blew themselves up on Friday, killing four Libyan soldiers who had granted them safe passage to leave buildings under Isis control, a spokesman for the government forces told Reuters.
Libyan forces, backed by US air strikes, are close to taking full control of the former Isis stronghold of Sirte after a campaign lasting more than six months.
But they are having difficulty dislodging Isis from a final patch of land near the city's Mediterranean sea front, partly because of concerns about families or captives still held by the militants.
During a pause in fighting on Friday, Reuters journalists reported seeing one woman escorting three young children through an alleyway, towards waiting Libyan forces.
Shortly after the children were driven away in an ambulance, there was a blast as the woman detonated her explosives, wounding around a dozen people.
Rida Issa, a spokesman for the Libyan forces, said two similar incidents, which he said were suicide attacks, had taken place as other women and children were leaving Isis-held ground.
Four members of the Libyan forces had been killed and 38 wounded, he added.
Several groups of families or hostages have been freed or escaped from Isis in Sirte in recent weeks, some of them refugees from sub-Saharan Africa who were captured by the group as they crossed Libya.
"The investigation will tell us whether these women were fighting with Daesh [Isis], or if they were captives," Mr Issa said of those who got out on Friday.
Isis took full control of Sirte in early 2015, imposing its ultra-hardline rule over the city in the following months.
Forces led by brigades from Misrata began a campaign to retake Sirte after Isis advanced towards their city in early May.
Additional reporting by Reuters
