Three U.S. citizens are among 37 defendants sentenced to death by a military court on Friday for their role in a May failed coup in the Democratic Republic of Congo.

Armed men briefly occupied an office of the presidency in capital Kinshasa on May 19 before their leader, U.S.-based Congolese politician Christian Malanga, was killed by security forces.

His son, Marcel Malanga, was among the Americans on trial, along with Marcel's friend, Tyler Thompson, who played high school football with him in Utah. Both are in their 20s.

The third American, Benjamin Zalman-Polun, was a business associate of Christian Malanga.

All three were found guilty of criminal conspiracy, terrorism and other charges, and sentenced to death in a ruling read on live TV.

Malanga had previously told the court that his father had threatened to kill him unless he participated. He also told the court it was his first time visiting Congo at the invitation of his father, whom he had not seen in years.

The Americans are among some 50 people, including U.S., British, Canadian, Belgian and Congolese citizens, standing trial following the failed coup.

A total of 37 defendants were sentenced to death.

The verdict was read out under a tent in the yard of Ndolo military prison on the outskirts of Kinshasa. The defendants were seated in front of the judge, wearing blue and yellow prison-issued tops.