Some 500 survivors in total were being pulled to safety, the coastguard told AFP. Spanish NGO Proactiva Open Arms, which was taking part in the rescues, said the bodies had been recovered by the Santa Lucia merchant ship.
"We are here to stop more people drowning, today eight dead and four drifting boats" in distress, Proactiva's founder Oscar Champs said on Twitter.
The charity said there were 79 women and 39 minors - including four young children - among those rescued.
Nearly 95,000 people have been brought to safety in Italy this year, a rise of one percent on the same period last year, according to the interior ministry.
At least 2,385 migrants have died during the perilous crossing since January, the International Organization for Migration (IOM) said.