The element of surprise was lost in a failed U.S. military raid to rescue two Western hostages being held by al Qaeda militants in Yemen, a senior Defense Department official said Saturday.

American photojournalist Luke Somers and South African Pierre Korkie, a “respected teacher” who was to be released on Sunday, were fatally shot in the compound by a terrorist as the secret mission unfolded, a U.S. official said.

The relief group Gift of the Givers, which was helping secure Korkie’s release, had recently informed his wife that “the waiting is almost over.” CNN reported earlier that Korkie worked for Gift of the Givers, but the relief group said that he did not.

“Three days ago, we told her ‘Pierre will be home for Christmas,'” said the group, which identified the South African hostage as Korkie. “We certainly did not mean it in the manner it has unfolded.”

He was an “innocent man, a respected teacher,” Korkie’s wife, Yolande, said in a video made before his death.

President Barack Obama ordered Friday’s mission because “there were compelling reasons to believe Mr. Somers’ life was in imminent danger,” Defense Secretary Chuck Hagel said.

A video of Somers pleading for his life was released earlier this week by al Qaeda in the Arabian Peninsula (AQAP). The U.S. was given three days to comply with unspecified demand. Time was running out.

Arrangements for Korkie’s release may have been missed by the White House.

The Obama administration assessed that there were two individuals at the location but did not know one was South African or that negotiations were underway for his release, a senior State Department official told CNN’s Elise Labott.

Korkie and his wife were abducted in May of last year, but AQAP subsequently let her go. On Friday, a team of local leaders was finalizing arrangements to reunite Korkie with his wife and children, the relief group said in a statement.

Obama’s decision

The President condemned AQAP’s killing of the two hostages and explained his decision to authorize the rescue attempt.

“Earlier this week, a video released by his terrorist captors announced that Luke would be killed within 72 hours,” Obama said in statement. “I also authorized the rescue of any other hostages held in the same location as Luke.”

Secretary of State John Kerry said in a statement that the President had received a recommendation to authorize the operation.

Obama offered his condolences to Somers’ family.

“I also offer my thoughts and prayers to the family of a non-U.S. citizen hostage who was also murdered by these terrorists during the rescue operation,” the statement read. “Their despair and sorrow at this time are beyond words.”

‘They lost the element of surprise’

The operation took place Friday at 5 p.m. ET, a U.S. official told CNN’s Barbara Starr.

On Thursday, the Defense Department became aware of enough new intelligence about the location of the hostages to stage a rescue mission, the official said. A senior Defense Department official traveling with Hagel in Afghanistan said that the operation was accelerated because there was intelligence that Somers would be killed on Saturday morning (Eastern time).

Obama and Hagel were briefed the next day.

Two Osprey aircraft transported a team of about three dozen U.S. Navy SEALs, mainly from SEAL Team Six, and a combat medical team near the captives’ location. There were no Yemeni forces with the U.S. commandos.

The official traveling with Hagel said that once the Ospreys landed, the team had to trek about 10 kilometers (6.2 miles) to the compound.

They were discovered at about 100 meters from the location where Korkie and Somers were being held, according to that official. The main part of the assault lasted 5-10 minutes.

“They lost the element of surprise at the last minute as they approached the compound,” the official told Starr.

It was not clear where the kidnappers were when the firefight started, but the official speaking with Starr said that U.S. is certain that someone ran back inside the compound and shot Korkie and Somers after the battle broke out. The official would not specify how they could be so certain of that detail.

Difficult, ‘precision’ mission

U.S. forces were on the ground for about 30 minutes, an official told Starr. They stayed for that length of time because the combat medical team was trying to stabilize the two wounded hostages.

According to another official, the hostages were loaded onto a plane and flown to a nearby U.S. ship.

One of the hostages died before reaching the ship. The other died afterward.

Drones and fighter jets patrolled overhead during the mission.

The U.S. forces that carried out the mission are safe, a U.S. defense official said. Both the President and Kerry praised their valor.

The hostages were being kept at a location close to another where U.S. and Yemeni forces had carried out a previous raid.

This rescue mission was particularly difficult, due in part to Yemen’s sparse population, retired Lt. Col. James Reese, global affairs analyst for CNN, said Saturday.

Reese noted that it would have been difficult for the military to travel a significant distance by air and still maintain the element of surprise in a rescue operation.

“It has to take precision,” he said. “This is like brain surgery.”

A previous attempt

It was the second such attempt by U.S. forces in two weeks.

In the first attempt in November, U.S. and Yemeni special forces outfitted with night visors embarked on the mission about a few miles from a cave where AQAP was holding hostages.

A gunbattle ensued, and the special forces killed all seven abductors and freed eight hostages. But the militants had separated Somers and four more hostages from the group and moved them to another location two days before the raid.

This week, AQAP released a video threatening to kill Somers and showing the American photojournalist pleading for his life.

A spokesman read a statement saying Somers would meet his inevitable fate if Washington did not meet the terror group’s demands. The spokesman did not name the demands but said the U.S. government knew what they were.

Pleading for his life

Somers’ brother and mother posted a response video to YouTube in which they pleaded with the militants to spare him.

“He is not responsible for any actions that the U.S. government has taken. Please understand that we had no prior knowledge of the rescue attempt for Luke, and we mean no harm to anyone,” Jordan Somers said.

Paula Somers thanked them for taking good care of him, but also asked her son be returned to her alive.

“Please show mercy and give us an opportunity to see our Luke again. He is all that we have,” she said.

Tik Root, a former freelance journalist, met Luke Somers when they were both in Yemen.

“Of all the people I met in Yemen, Luke is certainly not the person that should have happened to,” Root said on CNN’s “New Day Saturday.” “He was passionate about the country, its people, and he was just a very thoughtful, quirky guy.”

Root is now a desk assistant for PBS NewsHour, and he wrote about him Saturday morning on NewsHour’s website.

“I didn’t know him particularly well but we did cross paths about a dozen times,” Root said. “He was really dedicated to Yemen.”