BOSTON -- Friends and family are saying goodbye Tuesday to a Massachusetts Marine who was killed in Iraq last week.

NewsCenter 5's Shiba Russell reported that 28-year-old Sgt. William Callahan left behind a wife and a 3-week-old son, who Callahan never met.

The family requested a private funeral Mass. Friends said Callahan was a quiet man who would not want a lot of pomp and circumstance. Marines saluted Callahan's flag-draped coffin as it passed en route to the service.

"He was just always looking to better himself as a Marine," one man said.

Callahan's son, Daniel, was born 17 days after Callahan was killed in Iraq. His sacrifice was honored by hundreds, as a half-mile procession route was lined with red, white and blue.

"We wanted to be part of it and honor him and his family," said Leo Moreria.

"He gave up everything for us so that we could just be out here today," said Tim Webster.

Callahan's son is named after two fallen Marines. Callahan will be buried at Arlington National Cemetery on Thursday.