INDEPENDENCE, Mo. -- A soldier from Independence who had been in Iraq for one week has been killed in a roadside bombing, relatives said.

Defense officials said Spc. Shawn Rankinen, 28, and two other soldiers died early Wednesday when the Humvee in which they were traveling was struck by an explosive device north of Baghdad.

Betsy Rankinen, Shawn's 81-year-old mother, said he had just called her on Monday -- he told her that everything was great, he would be all right and that he would come home.

"He was telling us how great it was -- the barracks, the air, he had his new computer and phone, that he was really living high," Betsy Rankinen told KMBC's Dan Weinbaum.

Betsy Rankinen said her son enlisted in the Army last August after spending six years in the Navy. She said Shawn was restless and he loved the military life, so he joined the Army to drive tanks.

"He was gung-ho about it, so if he wants to do something like that, I'm right behind him 100 percent. I think the military is great for these kids," Betsy Rankinen said.

She said she took Shawn into her care when he was less than 3 months old and legally adopted him when he was 10 years old.

She said the shock of losing her son hasn't fully sunk in.

"I think to the other mothers grieving like I am -- I'm not the only one. It's a big sacrifice. They gave their life, and we're left," she said.

Over the years, Betsy Rankinen has been a foster mother to 40 children.

Funeral arrangements are pending.