Updated

Fort Carson (search), already hit hard by the conflict in Iraq, suffered its single heaviest combat loss since the Vietnam War with the deaths of four soldiers aboard a helicopter shot down near the Euphrates River.

Many of the victims of Sunday's attack had been headed out of Iraq for R&R or emergency leave. One, Fort Carson-based Sgt. Ernest Bucklew, 33, had been on his way home to attend his mother's funeral in Pennsylvania.

"Even on your worst day, he knew how to make you laugh," his wife, Barbara Bucklew, said through tears Monday. "That had to be his best quality."

In all, 16 U.S. soldiers died and 20 were wounded, including 13 from Fort Carson, in the deadliest single strike against U.S. forces since the invasion of Iraq in March. The military confirmed other casualties from Fort Campbell (search), Ky., and Fort Hood (search), Texas. Six of the soldiers killed and six wounded were based at Fort Sill (search), Okla., Fort Sill officials said Monday.

"We are going to be resolute in our commitment," Col. Michael Resty Jr., Fort Carson garrison commander, said Monday.

"I can tell you morale, despite the fact that we are taking casualties, is high," he said. "Unfortunately, we will probably have casualties in the future."

Fort Carson has sent 12,000 troops to Iraq -- its largest deployment since World War II -- including units from the 3rd Armored Cavalry Regiment, 3rd Brigade Combat Team and battalions of the 10th Special Forces Group. At least 21 soldiers from the post had already died there, all since President Bush declared an end to major combat on May 1.

Lt. Col. Tony Aguto, executive officer with the 3rd Armored Cavalry Regiment, told the Colorado Springs Gazette, "We are all just kind of reeling for the moment."

Officials at Fort Carson confirmed the troops were on their way home for R&R.

Pfc. Karina Lau, a 20-year-old trained at Fort Hood, planned to surprise her family in Livingston, Calif., with a two-week visit. "She had just e-mailed my wife just two hours before she got on the helicopter," her brother-in-law, Noel Rivera, said Monday. Lau died in the crash.

The Defense Department identified another victim as Staff Sgt. Paul A. Velazquez, 29. He was married and from San Diego, Fort Sill spokesman Master Sgt. Tony McKinney said. The names of the five others from Fort Sill who were killed in the crash were not released.

First Lt. Brian Slavenas, a 30-year-old Illinois National Guardsman from Genoa, Ill., was flying the helicopter when it went down, his father said Monday. He said his son loved his job.

"He described to me seeing all of those places from the air, pointing out archaeological sites like Babylon, and from the air, for him it was like sightseeing," Ronald Slavenas said.

Brian Slavenas' older brother, Marcus Slavenas, a Marine who served in Desert Storm, said: "I just feel like the whole world was cheated because he was just the wrong person for the good of the world to be killed."

Flags flew at half-staff Monday at the Peoria headquarters of Slavenas' F Company 106th Aviation Battalion.

"Your hearts go out to the families. You just pray that they'll find some comfort," said Lt. Col. Greg Crocher, the base's commander. He said more than 200 members of the unit have been in Iraq since April. Members are split between the Peoria base and a detachment in Davenport, Iowa, where officials have said four of the injured were based.

Bucklew, the son of a Pennsylvania coal miner, had recently e-mailed family, saying he didn't plan to take a 10-day leave because it would be too hard on his two sons back in Colorado, said his uncle, Jack Smith. But after his mother died Friday, he arranged through the Red Cross to return.

Fort Campbell spokesman George Heath said another of the victims was attached to the 101st Airborne Division, based at Fort Campbell.

Most of the soldiers injured in the helicopter crash were flown Monday to Germany for treatment at the U.S. military's Landstuhl Regional Medical Center. Nine were admitted to intensive care, including five in serious condition, said hospital spokeswoman Marie Shaw.

"They are being evaluated and surgeries are planned throughout the day," Shaw said.

At Fort Carson, the troops were saddened by the crash, but they are "also serious and professional and have to continue the mission," said Lt. Col. Thomas Budzyna.

Barbara Bucklew, who lives at Fort Carson, said one of the last e-mails her husband sent to her included his reminisces about times with his mother when he was a child.

"He said he couldn't sleep. He was thinking about her. He couldn't wait to be home," she said.