President Obama is scheduled to address a memorial service Sunday for the dozen men and women slain by a gunman at the Washington Navy Yard last week, according to the White House.

Obama and first lady Michelle Obama will visit with loved ones of the victims before the president speaks to the gathering about 5 p.m, officials said. The service to set to be held outdoors at the Marine Corps barracks at Eighth and I streets SE.

The 12 victims — nine men and three women, ages 46 to 73 — were killed Monday morning in the Navy Yard’s Building 197 when a contract employee working for the Navy opened fire, first with a shotgun, then a pistol. The 34-year-old assailant, Aaron Alexis, a former Navy reservist beset by mental problems, was killed after a lengthy gunfight with law enforcement officers, authorities said.