(CBS) — Four soldiers from an Indiana-based National Guard unit, including two from the Chicago area, have been killed in Afghanistan.

One of the fallen soldiers, Spc. Christopher Patterson, grew up in Aurora in a military family. The 20-year-old was attending Valparaiso University when he joined the Indiana National Guard.

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Patterson’s unit, the Valparaiso-based 713th Engineer Company, was on active duty in Afghanistan when their vehicle struck a roadside bomb.

“Chris didn’t have to go with his unit when it activated,” his mother, Mary Patterson, told CBS 2 on Saturday. “When they got news that the unit was being activated he said, ‘I have to do this. I didn’t sign up to just stay in school or to get an education. I did this for my country.’”

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Also killed was Spc. Brian Leonhardt, 21, of Merrillville, Ind.

Staff Sgt. Jonathan Metzger of Indianapolis and Spc. Robert Tauteris Jr. of Hamlet, Ind. also died.

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Another soldier, Pvt. Douglas Rachowicz from Hammond, Ind. was injured in the blast. He suffered a broken pelvis and collapsed lung.