CHICAGO -- A suburban Chicago college student who was killed during a track and field meet was struck by an errantly thrown hammer while standing near the field during warm-ups, authorities said Monday.

The hammer -- a steel wire attached to a heavy metal ball that can weigh as much as 16 pounds -- struck 19-year-old Wheaton College freshman Ethan Roser in the head during Saturday's meet, said Bill Murphy, Wheaton's deputy police chief. Roser, of Cincinnati, was volunteering at the meet and was going to measure the throws.

An autopsy conducted Monday by the DuPage County Coroner's office determined, as expected, that the preliminary cause of death was head trauma.

Wheaton Police are investigating the death of Wheaton College student Ethan Roser, 19, who was killed by an errant hammer throw during a meet. Courtesy Wheaton College

Murphy said investigators will continue to look into whether there was any criminal negligence, but that they don't suspect there was any. Wheaton College declined to say whether it would conduct its own investigation.

Students at the Christian college about 25 miles west of Chicago gathered after the meet to pray for Roser, who transferred there in January from a school in Cincinnati.

"It was time for us to come together and really turn to God in this tough time,'' student Phoebe Morris told the (Arlington Heights) Daily Herald.

Roser spent much of his childhood in Zimbabwe, where his parents were missionaries. His mother, Pat Roser, said Ethan's faith played a big role in how he dealt with a knee injury in high school.

"That just totally changed him, and he wanted to go and tell other young people about God,'' she told the newspaper. "That's what he was doing at Wheaton.''

Roser's father, the Rev. Mark Roser, described his son as "just a really special kid'' who considered his family members to be his best friends.

"We're having a really hard time saying goodbye and letting go,'' he told the paper. "We know God's in control, and he works everything out even though it's beyond our comprehension.''