The Black Hawk helicopter went down with 17 people aboard on a stretch of the Inirida River, in the country's southeastern Guaviare jungle region.

"Unfortunately, we have found the bodies of nine of our personnel," a military spokesperson said on Twitter.

The military did not say if the helicopter crashed or was shot down. Neither did it say anything about the other two soldiers who had been aboard the helicopter.

President Ivan Duque lamented on Twitter what he described as "an accident," and said the soldiers aboard the helicopter were supporting "operations against illegals."

According to the army, the helicopter was supporting a military sweep against FARC dissidents -- leftist guerrillas who refused to sign the peace deal their comrades reached with the government in 2016.

There are some 2,300 dissident guerrilla fighters, according to military intelligence estimates, who survive thanks to drug trafficking, illegal mining and an extense support network.

The area is also known for growing drug crops. Colombia is the world's top producer of coca leaves, the source plant for cocaine.