Four suicide bombers attacked the island of Koulfoua on the Chadian side of Lake Chad on Saturday, killing at least 15 people and injuring at least 130 others, two security sources reported.
The sources also said that the attacks were carried out on market day.
"Three suicide bombers blew themselves up in three different places at the weekly market on Loulou Fou, an island in Lake Chad," one of the sources who asked not to be identified said.
"The provisional death toll is 19 dead, including the four kamikazes, and 130 injured," said state TV.
There was no immediate claim for the attacks although the islands in Lake Chad have previously been targeted by Boko Haram militant group from neighbouring Nigeria.
Thousands of people who fled Boko Haram attacks in Nigeria were seeking asylum on the island earlier this year although it was not immediately clear if they were still based there.
The UN Officer for the Coordination of Humanitarian Affairs said this week that more than 50,000 internally displaced people had arrived in the region since the end of the July.
On Nov. 9, the capital N’Djamena declared a state of emergency in Lake Chad region after a twin suicide bomb attacks killed 12 people.
The decision gave the governor of the region the authority to ban the circulation of people and vehicles and power to search homes and seize arms.
The Chadian soldiers has been on the front line of a regional military operation against Boko Haram, whose attacks have spread from northeast Nigeria, its common stronghold, to the country’s three neighbours that border Lake Chad.