WASHINGTON (AP) — President-elect Joe Biden has marked the 48th anniversary of the accident that killed his first wife and baby daughter by attending Mass at the church where they are buried.

Neilia Biden and the couple’s 13-month old daughter, Naomi, were killed when their car was struck by a tractor-trailer as she took the kids to pick out a Christmas tree.

Sons Hunter and Beau were seriously injured. They were a year and a day apart in age, at 3 and 4.

Joe Biden had just been elected to the Senate and was in Washington setting up his new office at the time of the accident.

Biden and his wife, Jill Biden, attended the Friday morning service in Delaware at St. Joseph on the Brandywine, a Roman Catholic church. The campus of the church contains a large parish cemetery. After Mass, the Bidens walked to the gravesite markers to pay their respects.