Military officers in Mali detained the interim president, prime minister and defence minister on Monday.
That's what multiple sources told Reuters, just months after the country's former leader was ousted in a coup.
Sources said President Bah Ndaw, Prime Minister Moctar Ouane and defence minister Souleymane Doucoure were all taken to a military base in Kati outside the capital Bamako.
That came just hours after two members of the military lost their positions in a government reshuffle.
The military's ultimate goal was not immediately clear.
One official in Kati said this was not an arrest.
Their detentions could exacerbate instability in the West African country, where violent Islamist groups linked to al Qaeda and the Islamic State control large areas in the desert north.
The United Nations' mission in Mali called for the group's "immediate and unconditional" release and said those who hold the leaders would have to answer for their actions.
The region's top decision-making body, ECOWAS, said a delegation will visit Bamako on Tuesday to help resolve the "attempted coup."
Kati's military base is notorious for ousting Mali's leaders.
Last August, the military took President Ibrahim Boubacar Keita to the town of Kati and forced him to resign.