Al-Qaeda Fighters in Yemen Seemed Ready for SEAL Raid: Source The White House said Tuesday "tremendous" intelligence was gathered in the raid.

 -- Al-Qaeda fighters seemed ready for Sunday's deadly Navy SEAL raid in Yemen, a source familiar with the action told ABC News, almost as though they knew the Americans were coming.

The raid succeeded in obtaining "a tremendous amount" of information about al-Qaeda in the Arabian Peninsula (AQAP), White House press secretary Sean Spicer said Tuesday, though one SEAL was killed and three others were wounded in a firefight with AQAP members. Three additional service members were injured when an aircraft sent to medevac the SEALs experienced a hard landing that left it inoperable.

The SEALs' mission was intended to gather intelligence about the terrorist group's senior leadership and its plotting efforts outside the region. The mission was also intended to capture any AQAP leaders if possible, but no one was detained in the raid, said a U.S. official.

"Obviously, we recovered a tremendous amount of information, and we killed an estimated 14 members of [AQAP] individuals," Spicer told reporters at the White House on Tuesday.

An unnamed U.S. official told ABC News that electronics with data were seized in the raid and it is hoped that information from the action could prevent terrorist attacks targeting the West.

The al-Qaeda affiliate has been able to exploit the security vacuum created in Yemen by fighting between Iranian-backed Houthi militants and a Saudi-led military coalition seeking to restore the government overthrown by the Houthis.

In the works for months, the raid was authorized by President Donald Trump and targeted a three-house compound in southern Yemen that was used by AQAP leaders as an operational staging area. "There were operational reasons why it happened when it did and not two weeks ago,” Capt. Jeff Davis, a Pentagon spokesman, said Monday about the timing of the raid.

Taking advantage of a moonless night, members of the elite unit SEAL Team Six flew to the compound aboard Marine MV-22 tilt-rotor aircraft from the USS Makin Island, a Navy amphibious ship operating in the Gulf of Aden in the Arabian Sea, a U.S. official said.

Accompanying the SEALs on the raid were dozens of special operations forces from a partner nation in the region, the source familiar with the raid told ABC News.

With armed drones flying overhead, the SEALs arrived at the compound under the cover of darkness and immediately took heavy fire, the source said.

According to the source, it was clear that the AQAP fighters in the compound knew the Americans were coming and engaged them with heavy weapons.

On Monday, Davis said there were women among the AQAP fighters who "ran to pre-established positions as though they had trained to be ready and trained to be combatants and engaged with us."

An intense firefight at close quarters killed Chief Special Warfare Officer William "Ryan" Owens, 36, of Peoria, Illinois, and left three other SEALs wounded.

A Marine MV-22 Osprey was called in to evacuate the wounded, but in the darkness it experienced a hard landing, injuring three other American service members.

The Pentagon said at least 14 AQAP fighters were killed in the raid, and there are unconfirmed reports from Yemen that civilians were also killed in the firefight. U.S. officials are taking those allegations seriously and said they are still assessing whether there were civilian casualties.

Earlier today, Trump had "a very somber and lengthy conversation" with Owens' family, according to Spicer.

"The president offered his sincerest condolences to Officer Owens' wife, his father and their three children," said Spicer. "We could never repay the debt of gratitude we owe him, the freedoms that he fought for and the sacrifice that he made, as well as the other members of his unit who were injured in this operation."

Owens enlisted in the Navy in 1998 and served with Navy special warfare units since 2002. Spicer said Owens was on his 12th overseas deployment.