According to a report in a Christian blog  http://www.cgg.org/index.cfm/fuseaction/Library.sr/CT/RA/k/274/No-Greater-Love.htmthe February 13, 1987, issue of The Missileer, a newspaper of the 45th Space Wing, U.S. Air Force, ran this brief and apparently true story by Colonel
John W. Mansur:

The mortar rounds landed in an orphanage run by a missionary group in the small Vietnamese village. The missionaries and one or two children were killed outright and several more children were wounded, including one girl about eight years old.

People from the village sent for help to a neighboring town that had radio A blood transfusion was imperative so a donor with a matching blood type was required. A quick test showed that neither American had the correct blood type, but several of the uninjured orphans did.

The doctor spoke some pidgin Vietnamese, and the nurse a smattering of high-school French. Using that combination together with much impromptu sign language, they tried to explain to their young, frightened audience that unless they could replace some of the girl's lost blood, she would certainly die. Then they asked if anyone would be willing to give blood to help.

Their request was met with wide-eyed silence. After several long moments, a small hand slowly and waveringly went up, dropped back down, and then went up again.

"Oh, thank you," the nurse said in French. "What is your name?"

"Hung," came the mumbled reply.

Hung was quickly laid on a pallet, his arm swabbed with alcohol, and the needle inserted in his vein. Through this ordeal Hung lay stiff and silent. After a moment, he let out a shuddering sob, quickly covering his face with his free hand.

"Is it hurting, Hung?" the doctor asked.Hung shook his head, but after a few moments another sob escaped, and once more he tried to cover up his crying. Again the doctor asked him if the needle
hurt, and again Hung shook his head.

But now his occasional sobs gave way to a steady, silent crying, his eyes screwed tightly shut, his fist in his mouth to stifle his sobs.The medical team was concerned because the needle should not have been hurting him. Something was obviously very wrong. At this point, a Vietnamese nurse arrived. Seeing the little one's distress, she spoke to him, listened to his reply, and answered him in a soothing voice.

After a moment, the boy stopped crying, opened his eyes and looked questioningly at the Vietnamese nurse. When she nodded, a look of great relief spread over his face. Looking up, the Vietnamese nurse said quietly to the Americans, "He thought he was dying. He misunderstood you. He thought you had
asked him to give all his blood so the little girl could live."

"But why would he be willing to do that?" asked the navy nurse.The Vietnamese nurse repeated the question to the little boy, who answered simply, "She's my friend."

Greater love has no man than this, that he lay down his life for a friend.