The death of Lance Cpl. Anthony Aguirre, 20, of Channelview, Texas, marks the 23rd from the 2nd Battalion, 3rd Marine Regiment at Kane'ohe Bay since their seven-month deployment got under way in September. Joe Hermosa • Valley Morning Star via AP

"We would tease him and tell him, 'You're a civilian now, Anthony,' " his sister, Christina Castillo, told the Houston Chronicle. "You can take off your uniform."

"He was a great person," she added. "A proud Marine and he loved his family."

Aguirre, assigned to 2nd Battalion, 3rd Marine Regiment based at Kane'ohe Bay, died Monday during combat operations in Iraq's Al Anbar province, the Department of Defense announced today.

Aguirre's death marks the battalion's 23rd since its seven-month deployment began in September.

Aguirre joined the Marine Corps in August 2005 and reported to Hawai'i in February 2006. He deployed to Iraq on Sept. 11, the fifth anniversary of the terrorist attacks, his family said.

"When I thought of all the days for him to leave," said Castillo, "he had to leave on this cursed day."

His awards include the Purple Heart, National Defense Service Medal, Iraq Campaign Medal, Global War on Terrorism Service Medal, and Sea Service Deployment Ribbon.

Two staff sergeants showed up at his sister's house Monday morning to inform the family that Aguirre had been killed.

Castillo said she had just gotten up to get her children ready for school when she heard the knock at the door at about 6 a.m.

"I knew instantly when I saw them what they were there for," said Castillo, 28, who helped raise Aguirre since he was in the eighth grade. "My heart just fell."

Castillo told Houston Chronicle that the sergeants said her brother had been killed near an explosion. They gave her no further details.

Aguirre's father, Arturo Aguirre, told KGBT TV in

Harlingen, Texas, that he wants people to remember his son just as he remembers him, "joking, playing and friendly with everybody."

Aguirre's mother, Leticia Loa, drove to Raymondville to join Aguirre's father and other family members after learning of her son's death early Monday. They were planning a memorial service in Raymondville followed by the funeral in Houston, said Hilda Trevino, a cousin who has been acting as a family spokeswoman.

Aguirre was born in Harlingen, lived in Raymondville, Texas, for a few years, then graduated from Channelview High School in Houston.

He had participated in military training programs since elementary school, was active in JROTC and joined the Marines about a year after graduating from high school.

"He always wanted to join," his sister said. "It was never a question."

She spoke to her brother for the last time in mid-February; he called to tell her he was returning home on April 15.