This undated photo released by the Boston Fire Department via Twitter shows Lt. Edward J. Walsh, killed Wednesday, March 26, 2014, when trapped in the
This undated photo released by the Boston Fire Department via Twitter shows Lt. Edward J. Walsh, killed Wednesday, March 26, 2014, when trapped in the basement while fighting a fire in an apartment building in Boston. Walsh, 43, and a father of three, was assigned to Engine 33, and had been a firefighter for almost a decade. (AP Photo/Boston Fire Department) (Uncredited)

WATERTOWN, Mass. (AP) -- A 43-year-old Boston firefighter killed with a colleague as they fought a nine-alarm apartment fire last week is being laid to rest.

Lt. Edward Walsh died alongside 33-year-old firefighter Michael Kennedy when they became trapped in the March 26 blaze at a Back Bay-area brownstone building. Walsh was married with three children all under the age of 10.

His funeral Mass is scheduled for Wednesday morning at St. Patrick's Church in suburban Watertown, where he grew up.

Thousands, including firefighters from across the country, attended his wake Tuesday.

Walsh will be buried next to his father, a Watertown firefighter.

Kennedy's wake is scheduled for Wednesday afternoon. His funeral is Thursday in Boston's West Roxbury neighborhood.

Fire department chaplains will conduct the funerals. Boston Cardinal Sean O'Malley is expected to attend.