Biden marks anniversary of tragic death of his first wife and one-year-old daughter in car crash in 1972 at private mass with Jill, Ashley, Hunter, Melissa and Baby Beau

President Joe Biden took a break from politics on Monday to mark the anniversary of the deaths of his first wife and daughter.

The president attended a private Mass at Joseph on the Brandywine in Wilmington, Del., with first lady Jill Biden. They were accompanied by their daughter Ashley. Hunter Biden, his wife Melissa and their son Beau were also in attendance.

Biden's first wife Neilia Hunter Biden and their one-year-old daughter Naomi were killed in a car accident on this date in 1972. The two are buried in the cemetery at the church.

Neilia and Naomi were killed when their car was hit by a tractor-trailer as she took the children to pick out a Christmas tree. Biden's sons Hunter and Beau were also in the vehicle and were seriously injured. They were a year and a day apart in age, at 3 and 4 years.

Joe Biden in 1972 with his wife Neilia and daughter Naomi and sons Hunter and Beau

President Joe Biden and First Lady Jill Biden arrive at Saint Joseph at Brandywine Catholic Church on the anniversary of Neilia and Naomi's deaths

Beau later died of brain cancer in 2015 at the age of 46. He is also buried in Joseph on the Brandywine. Hunter Biden and his wife Melissa named their son Beau in honor of Beau Bide.

The deaths of his first wife and young daughter haunted Biden's early political career. He had just been elected to the Senate – winning his first election in November 1972 – when the accident occurred.

Biden often tells the story of their deaths — praising the first responders who helped his family — and admitting that he considered resigning from the Senate even before taking the oath of office.

He remained in office on the advice of other senators. He was sworn into the Senate at the Wilmington hospital where Beau and Hunter Biden were treated after the accident.

As a senator, Biden began commuting daily between Wilmington and Washington, D.C. — it's about a 90-minute train ride — so he could be with his young sons while they recovered. His sister Valerie and other family members helped.

Biden married Jill Jacobs in 1977 and they had a daughter, Ashley.

He continued his commute during his time as senator and vice president. As president, he regularly spends weekends in Wilmington, where he and Jill have a home.

President Joe Biden – together with Jill Biden – regularly attends mass on the anniversary of the death of his first wife and daughter

President Joe Biden, First Lady Jill Biden and Hunter Biden – along with wife Melissa and son Beau – leave Saint Joseph at Brandywine Catholic Church

Biden was sworn into the Senate in 1973 at the Wilmington hospital where Beau and Hunter Biden were treated after the accident that killed their mother Neilia and sister Naomi.

Senator-elect Joseph Biden and his wife Nelia cut his 30th birthday cake at a party in Wilmington, on November 20, 1972, with their sons Hunter and Beau

Biden left the White House on Sunday to attend the anniversary in his home state. He normally goes to church on December 18 to mark the death of Neilia and Naomi. Hunter Biden named his eldest daughter Naomi in honor of his late sister.

On Sunday evening, the president and first lady were leaving dinner with their campaign staff when a car plowed into their motorcade in downtown Wilmington.

Biden showed up frozen in shock when a car rammed an SUV that was part of his motorcade before Secret Service agents rushed him into a vehicle and drove him from the area Sunday evening.

A group of reporters and photographers captured the dramatic footage that showed the president being rushed into the back of his armored SUV by Secret Service agents, not knowing if the crash was part of a deliberate attack.

The wreck occurred as Biden was walking out of a building. As the loud bang sounded, Biden muttered 'Wow!' if he looked at the sound and seemed surprised.

The Secret Service seemed as baffled as the man they were protecting. They appeared to be moving slowly towards the target, taking almost ten seconds to bundle the country's leader into the safety of his vehicle.

The car involved in the crash was a silver Ford sedan with Delaware license plates. He crashed into the side of a black U.S. Secret Service SUV shielding the motorcade.

The sedan attempted to enter the closed intersection before Secret Service personnel sprang into action and surrounded the vehicle with weapons drawn, ordering the driver to put his hands up.

The driver's name has not been released.