MASSILLON, Ohio — When the phone rang at 11 p.m. on Saturday and Chiquita Seesan heard her son was hurt by a bomb in Iraq, she initially thought it was a prank call.

She soon found out this was no joke. Her son, 1st Lt. Aaron Seesan, was being flown to Germany after suffering third-degree burns over 80 percent of his body. He died the next day in Germany.

“He was tended to by the best surgeons in the world, and he was not in pain and he was surrounded by Americans who were his comrades and who respected him,” said Chiquita Seesan, who found out her son died when military officials visited her home Sunday night. “He died a hero.”

Aaron Seesan, 24, was serving with the 73rd Engineering Company out of Fort Lewis, Wash., his mother said. He was part of a unit in charge of diffusing mines and other bombs.

He died when a bomb struck the gas tank of the vehicle he was...