Christians are among five Nigerian men to have been executed in Nigeria by Islamist extremists.
The deaths were recorded in a 35-second video posted to YouTube by Eons Intelligence before being removed.
It showed the men blindfolded and kneeling in front of five militants standing behind them holding AK-47 rifles.
One of the executioners then spoke to the camera before the executions were carried out to warn other Christians that they would be next if they did not stop sharing the Gospel and convert to Islam.
"This is a message to all those being used by infidels to convert Muslims to Christianity," one of the executioners said, according to Morning Star News.
"We want you out there to understand that those of you being used to convert Muslims to Christianity are only being used for selfish purposes.
"And that is the reason whenever we capture you, they don't care to rescue you or work towards securing your release from us; and this is because they don't need you or value your lives. We therefore, call on you to return to Allah by becoming Muslims. We shall continue to block all routes [highways] you travel.
"If you don't heed our warning, the fate of these five individuals will be your fate."
After he finished his message, the five men were shot dead.
A Borno resident told Morning Star News that the three Christians were: Ishaku Yakubu, an aid worker from Chibok with Action Against Hunger who was a member of the Church of the Brethren (EYN); Luka Filibus, an aid worker from Monguno with the International Rescue Committee and also an EYN member; and Joseph Prince, a private security firm worker who was a member of the Redeemed Christian Church in Maiduguri.
The perpetrators have been identified as members of Boko Haram splinter group the Islamic State in West Africa Province (ISWAP).
The other two victims in the execution are believed to have been Muslim.
ISWAP had reportedly requested $500,000 for their release.
Christian Solidarity Worldwide's Chief Operating Officer Scot Bower said the military must be strengthened to protect Christians and others in northern Nigeria.
"CSW extends its deepest condolences to the families of Abdulrahman Babagana, Darman Dungus, Joseph Prince, Ishaku Yakubu, and Luka Filibus. These cowardly executions constitute a gross violation of international law, and we condemn them in the strongest terms," he said.
"Once again a death cult that goes to the most appalling lengths to extort money and garner headlines has deprived the world of dedicated, courageous individuals who worked selflessly to assist vulnerable communities in a dangerous area.
"We urge the Nigerian government to adequately resource the military units serving in the north east of the country, enabling them to address the terrorist threat decisively, and to offer adequate protection for civilians."