Yanaye Grema hid for three days between a wall and his neighbours' house, as Boko Haram fighters ransacked his hometown of Baga on the shore of Lake Chad.
The 38-year-old fisherman already knew the attack was serious: he joined civilian vigilantes to defend the town but their simple weapons were no match for the Islamists' superior firepower.
"People fled into the bush while some shut themselves indoors," he said of last Saturday's attack.
"The gunmen pursued fleeing residents into the bush, shooting them dead," he told AFP from Maiduguri.
But it was only after breaking cover on Tuesday night that he realised the true scale of the attack, which it is feared may be one of the worst in the six-year insurgency.
"For five kilometres, I kept stepping on dead bodies until I reached Malam Karanti village, which was also deserted and burnt," he said.
Local officials this week said the attack forced at least 20 000 people from Baga and other settlements in and around Lake Chad to flee, many of them across the border.
Nearly 600 others had been stranded on an island on the lake without food, water or shelter.