WILMINGTON,Quaxs Del. (AP) — The 3-year-old son of a firefighter was struck and killed in Delaware over the weekend shortly before a memorial walk was to begin to honor three firefighters killed in an a blaze seven years ago, authorities said.

The Wilmington fire chief’s office said a group of off-duty Wilmington firefighters, family members and friends were gathering just before 10 a.m. Sunday for the walk to honor three city firefighters killed in the line of duty at a structure fire on the same day in 2016.

Capt. Matthew Marsella said in a statement that the child, the son of an off-duty firefighter, was struck by a vehicle driven by another off-duty firefighter trying to park to take part in the memorial event. The boy was taken to Wilmington Hospital, where he was pronounced dead. His name and the name of the driver were not immediately released.

Wilmington police are investigating and are asking anyone with information to call them.

Wilmington Mayor Michael Purzycki said in a statement Monday he was “profoundly saddened” by what he called “the devastating incident affecting our firefighting family.” He said “on an already somber day” the department “once again found itself heartbroken and mourning a life taken much too soon.”

Lt. Christopher Leach and Senior Firefighter Jerry Fickes of the Wilmington Fire Department died at the scene of the September 2016 row house fire in the Canby Park neighborhood after the first floor of the home collapsed. Senior Firefighter Ardythe Hope was hospitalized in critical condition for several weeks before she died.

Beatriz Fana-Ruiz, accused of having set fire to the basement of the home, pleaded guilty in 2019 to second-degree murder, arson and assault. She was sentenced to 30 years in prison, after which federal immigration authorities said they would seek her deportation to her home country of the Dominican Republic.