Witnesses say two suicide bombers have carried out simultaneous attacks at buildings in the Chadian capital, causing multiple casualties.

An Associated Press reporter heard the explosion that shook a building in N'Djamena Monday morning.

A police official who spoke on condition of anonymity as he was not authorized to speak to the media said at least 10 people had been killed in that attack.

A second explosion went off at a police academy in the capital at the same time, witnesses said.

While there was no immediate claim of responsibility, suspicion fell on Boko Haram. The Nigerian Islamic extremist group has threatened to attack Chad because the country has supported Nigeria's military in its fight against the insurgent group.