WILMINGTON, Del. — President Joe Biden and his family held a private memorial service Sunday to mark the 50th anniversary of the car crash that killed his first wife and their baby daughter.

Biden, who had just been elected to the Senate in November 1972, was not in the car when his wife, 30-year-old Neilia, and their 13-month-old daughter, Naomi, were broadsided by a tractor-trailer on Dec. 18 of that year as they went out to buy a Christmas tree.

The couple’s two sons, Beau and Hunter, who were just about to turn 4 and 3 at the time, were also in the car and were seriously injured.