Afghanistan’s stepped-up summer fighting season has claimed the lives of three more Schofield Barracks soldiers who are part of a bulwark of receding U.S. forces in deadly Kunar province.

1st Lt. Dimitri A. Del Castillo, 24, of Tampa, Fla., and Staff Sgt. Nigel D. Kelly, 26, of Menifee, Calif., were killed Saturday when enemy forces attacked their units with small-arms fire, the Pentagon said.

On Sunday, Spc. Kevin J. Hilaman, 28, of Albany, Calif., also was killed by small-arms fire.

All three were killed during a large-scale operation in the Watapur district of Kunar involving hundreds of Schofield soldiers and Afghan forces airlifted in by helicopter to root out enemy fighters.

Maj. David Eastburn, a 3rd Brigade spokesman, said by phone from Afghanistan Tuesday that he couldn’t reveal the name of the operation, which started Saturday.

Ten Schofield soldiers with the 3rd Brigade Combat Team have been killed in mountainous and rebellious Kunar — the site of some of the greatest U.S. losses in the 10-year war — since the unit’s 3,500 soldiers left in March. Another Hawaii soldier who died in Kunar on the deployment is a suspected suicide, officials said.

Nate Pulliam, Del Castillo’s father-in-law, told The Tampa Tribune that his son-in-law was calling for support during a pitched battle when he was mortally wounded.

"He continued talking on the radio to get support," Pulliam said. "He died soon after getting hit, while remaining on the radio attempting to get fire support for the attack coming from multiple directions."

Pulliam told the newspaper that 28 other soldiers were wounded in the attack in the mountains of Kunar.

Del Castillo and his wife, 1st Lt. Katie Del Castillo, were on this deployment together with the 3rd Brigade; she was at another forward operating base in Afghanistan. They had met at West Point, were commissioned as officers in 2009 and married in December, the Tribune reported. Eastburn said she has returned to the mainland after her husband’s death.

"Our thoughts and prayers are with his family and friends at this time," Eastburn said.

Carmen Gentile, a reporter for USA Today with the 3rd Brigade, reported Monday that the operation in Watapur was being met by fierce resistance.

"We’re trying to kill every terrorist in the area," Maj. Pat Stitch, the 3rd Brigade’s operations officer, was quoted as saying. Stitch said the hope was that the Afghan army could "hold what we cleared."

The operation is the largest by the 3rd Brigade since it arrived in Afghanistan in April, Eastburn said.

Hilaman was assigned to the 2nd Battalion, 35th Infantry Regiment. He joined the Army on March 7, 2003, as an infantryman. This was his third overseas deployment. Del Castillo also was assigned to the 2nd Battalion, 35th Infantry Regiment.

Kelly joined the Army Aug. 20, 2003, as a combat engineer, and he was assigned to the 3rd Brigade Special Troops Battalion.

Two Schofield Barracks soldiers died in combat last week in Kunar province. Four others died last month when a homemade bomb exploded on May 23.

The loss of 10 soldiers in combat just a quarter into the 3rd Brigade’s yearlong deployment weighed heavily on the minds of some yesterday in Wahiawa, near Schofield Barracks.

Sgt. Brittney England, 27, returned June 20 from deployment to Iraq with Schofield’s 2nd Brigade.

"I used to be in the 3rd Brigade for 15 months," she said. "I have friends over there now. It’s very hard dealing with that, not knowing if that is your friend." She said she did not know Del Castillo, Kelly or Hilaman.

"I’m a medic so it makes it very hard," she said. "You have to work on them. We all signed up for this, so it’s our job. It’s our choice."

Molly Walker, owner of Molly’s Smokehouse in Wahiawa, said, "I have seen pictures of the soldiers who died on TV. I just know them as customers. But it’s just a strong sense of compassion for what they gave up to defend our nation. It’s huge."

Walker said she keeps in touch with some soldiers by email. "When there’s a casualty, you notice there’s a change in tone," she said. She is assembling goodie bags to send to the troops, "anything to lift their spirits," she said.

Violence has been on the rise across Afghanistan since the country’s Taliban Islamists launched a spring offensive and promised retaliation for the death of al-Qaida leader Osama bin Laden in a U.S. raid in Paki­stan on May 2.

NATO has recently withdrawn many of its combat troops from forward operating bases and combat outposts in Kunar and Nangarhar. Both provinces continue to be heavily contested by Taliban fighters, and Afghan border officials say Pakistani Taliban have moved in behind fleeing civilians in the border area.

"It’s nasty territory — it’s rocky, it’s dangerous, it’s on the Pakistan border — but our soldiers are making a difference there," said Master Sgt. James Guzior, a 25th Infantry Division spokesman at Schofield.

The 3rd Brigade operates in Kunar and Nangarhar provinces from fewer than 10 forward operating bases and multiple combat outposts, Eastburn said.

Spc. Brian Walker, a Schofield soldier at Combat Outpost Honaker-Miracle near the Pech River and Watapur valleys who was wounded May 13 by a roadside bomb, said in a recent Army story that "we get shot at all the time, every day."

Staff writer Leila Fujimori and The Associated Press contributed to this report.