Satellite images of the "catastrophic" attacks on two towns in Nigeria by Boko Haram militants have been released by Amnesty International.
The campaign group says the pictures, taken on 2 and 7 January, provide "indisputable and shocking evidence" of the scale of the assaults on Baga and neighbouring Doron Baga.
It believes hundreds of people were killed and that over 3,700 structures were either damaged or destroyed in the attacks.
Other nearby towns and villages in north-eastern Borno state were also targeted by the Islamists between 3 and 7 January.
"These detailed images show devastation of catastrophic proportions in two towns, one of which was almost wiped off the map in the space of four days," said Daniel Eyre, Nigeria researcher for Amnesty.
"Of all Boko Haram assaults analysed by Amnesty International, this is the largest and most destructive yet. It represents a deliberate attack on civilians whose homes, clinics and schools are now burnt out ruins."
Approximately 620 structures were damaged or destroyed by fire in Baga, a densely-populated town less than two square kilometres in size.
In Doron Baga, which is also known as Doro Gowon and is around four square kilometres, over 3,100 structures were either damaged or burnt.
Many of the wooden fishing boats along the shoreline, visible in the images taken on the 2 January, are no longer present in the 7 January photos.
This tallies with eye witnesses' testimony that many terrified residents fled to safety in boats across Lake Chad.
A man in his fifties told Amnesty: "I saw maybe around 100 killed at that time in Baga. I ran to the bush. As we were running, they were shooting and killing."
Other witnesses described how Boko Haram drove into the bush rounding up women, children and the elderly.
A woman who was detained for four days said: "(They) took around 300 women and kept us in a school in Baga. They released the older women, mothers and most of the children after four days but are still keeping the younger women."
Boko Haram fighters have repeatedly targeted communities for their perceived collaboration with Nigeria's security forces.
Towns that formed state-sponsored militia groups known as the Civilian Joint Task Force (Civilian JTF) have suffered particularly brutal attacks.
Since 2009 Amnesty says thousands of people have been killed, hundreds abducted and hundreds of thousands forced to leave their homes by Boko Haram.
It is calling on Nigeria's security forces to do more to protect civilians and for the group's "war crimes and crimes against humanity" to be "duly investigated".
