JOHANNESBURG - South African Pierre Korkie was just a day from freedom, after being held captive for 18 months by al-Qaida in Yemen, when he was killed in a U.S. rescue attempt Saturday, according to the non-governmental group Gift of the Givers.

Korkie, one of two hostages killed in the military effort, had been working as a teacher in Yemen before he was kidnapped. Negotiators said they had reached agreement for him to be released Sunday.

"A team of Abyan (Yemeni) leaders met in Aden this morning and were preparing the final security and logistical arrangements, related to hostage release mechanisms, to bring Pierre to safety and freedom," said Imtiaz Sooliman, founder of Gift of the Givers. "It is even more tragic that the words we used in a conversation with Yolande at 5:59 this morning was: 'The wait is almost over.'"

Korkie was kidnapped in the Yemeni city of Taiz in May 2013, along with his wife Yolande, who was doing relief work there. She was released in January without ransom as a result of negotiations by the South African relief group.

However al-Qaida militants demanded a $3 million ransom for Korkie's release, according to those close to the negotiations. Although the ransom demand was dropped, the kidnappers demanded a "facilitation fee," said the aid group. The undisclosed amount was raised by Korkie's family and friends, according to the South African Press Agency (SAPA).

On Nov. 26 an agreement was reached for him to be released and he was to be freed on Sunday, said Sooliman, founder of Gift of the Givers, a prominent aid group in South Africa.

Korkie was killed early Saturday morning when U.S. forces swooped in to try to free him and fellow hostage, American Luke Somers.

"The psychological and emotional devastation to Yolande and her family will be compounded by the knowledge that Pierre was to be released by al Qaida tomorrow (Sunday)," Gift of Givers said in a statement Saturday. Korkie, 56, is survived by his wife and two children.

Speaking Saturday, Sooliman said: "You can't blame anybody for this. You can't accuse or blame them (the U.S. forces). It's just unfortunate that it happened."

Korkie was a dedicated teacher, said a family friend. "Teaching was his life. His heart took him to Yemen. He loved teaching the poor," said Daan Nortier, who is acting as a family spokesman.

Korkie's body is currently held by the U.S. forces and the South African government will work with the U.S. military and the Yemeni government for the repatriation of his remains, said Nelson Kgwete, spokesman of South Africa's Department of International Relations.

Among the many South Africans expressing sorrow at Korkie's death was South African runner Zola Budd, who was once coached by Korkie. Budd is devastated, her manager Ray de Vries said in a statement Saturday, according to the South African Press Agency.

Earlier this year, Budd participated in South Africa's Comrades Marathon and dedicated her run to Korkie and appealed for his release.

News from © The Associated Press, 2014