The service was held at St. Patrick’s Church on Main Street. Mourners waited in line for hours to get inside.
"Thank you to all who honored Lt. Ed Walsh today," the Boston Fire Department said in a statement. "Your support and the comfort you provided was most welcome."
Walsh, who lived in West Roxbury, grew up in Watertown. His father and uncle, now deceased, served on the Watertown Fire Department. His cousin, Tom, is currently a captain there.
Walsh was married and had three children all under the age of 10.
His funeral will be held at the church Wednesday at 10:30 a.m.
Services for Mike Kennedy, the other fallen firefighter, start Wednesday.
Close to 20 more first responders were hurt in Wednesday's fire. Officials say the blaze may have started in a heating system, according to Boston.com. Arson was ruled out.
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