KARE 11 -- MINNEAPOLIS -- Three U.S. soldiers killed this week in an attack on a base outside Iraq's second largest city were members of the Minnesota National Guard, marking the deadliest day for Minnesota troops since 2005.

Wilcox had been on his first deployment to Iraq since May, his mother said Friday.

"He was a very proud young man, just very proud to serve his country," said Charlene Wilcox.

Carlos Wilcox grew up in Minnesota and graduated from Tartan High School in Oakdale, his mother said. He studied at Arizona State University and spent time studying in Granada, Spain. He then returned to Minnesota and graduated from Metro State University with a biology degree.

"He wanted to become a doctor," Charlene Wilcox said. "I had just sent him books to study for the MCAT (entrance exam) so he could apply for medical school."

Friends say Carlos Wilcox was a good friend -- someone you could go to for help or a smile.

"He was always happy. He was always smiling. He had a huge smile you could see from miles away," said Nicole Fox, Carlos' friend.

"Carlos was a really, really great guy, and they say only the good die young, and I guess that's the case here," Fox said.

The soldiers were members of the Minnesota National Guard's 34th Red Bull Infantry Division based in Rosemount. A spokesman for the unit, Capt. Paul Rickert, declined to comment, citing the military's waiting period for releasing casualty information. An official military release wasn't expected until Saturday.

The last time three Minnesota soldiers were died on the same day in Iraq was Feb. 21, 2005, when three National Guard troops were killed by a roadside bomb in Baghdad.