Houston Chronicle -- ROUND ROCK — A 24-year-old Marine reservist killed in an explosion during a combat operation in Iraq was moved to enlist by the Sept. 11 terrorist attacks.

Cpl. Steven P. Gill, of Round Rock, died Thursday near Zaidon, Iraq, after an improvised explosive went off. He had embarked on his first tour of duty in Iraq in March.

"We've lost a piece of our heart today," said Bill Gill, the Marine's father.

At least 159 Texas service members have died in Iraq since the war began in March 2003, according to the U.S. Department of Defense.

Gill enrolled at Concordia University, studying at campuses in Austin and Lake Forest, Ill., after graduating from Westwood High School in 1999.

His father said Gill had planned to enter the seminary. He later decided to be a youth minister because of his love of children and his own involvement in church youth groups.

Then came the Sept. 11 attacks.

"He was moved by what happened on 9-11," Bill Gill said. "When he saw those towers crashing, he had to do something."

While Steven Gill wanted to enlist immediately, his father persuaded him to finish the semester. In January 2002, Gill joined the Marines.

He was assigned to the 4th Marine Division, 4th Reconnaissance Battalion of San Antonio. That's the same unit his father served in years ago.

His brother, 27-year-old James Gill, is a member of the Army National Guard.

"He knew the sacrifice he might be called to make, and he accepted that," his father said.