Saturday's service for Christina Anderson and 8-year-old Ethan Anderson at the Guardian Angels Roman Catholic Church in Santee was open to the public.
"For the death of Tina and Ethan there are no easy words," the Rev. Kevin Casey told the memorial gathering, according to the Los Angeles Times (http://lat.ms/157LSe3 ). "We are touched by this evil and we can never be the same again."
The pair was found at the home of James Lee DiMaggio, who set it ablaze earlier this month and then took off with Hannah Anderson.
DiMaggio was killed by FBI agents Aug. 10 in the Idaho wilderness, ending a 6-day search that spanned much of the western United States and parts of Canada and Mexico.
Authorities have declined to discuss a possible motive in the deaths and haven't addressed other details of the case, including how Hannah was treated by DiMaggio during the ordeal.
"We struggle with deaths like this because they are not right. They are an abomination," Casey said.
Investigators have said DiMaggio set fire to his home using a timer, giving him a 20-hour jump on law enforcement.
DiMaggio's family has requested paternity tests to determine if the suspect fathered the children.
Hannah's father, Brett Anderson, gave his DNA to investigators to confirm Ethan's identity. DiMaggio named Hannah's grandmother, Bernice Anderson, as the sole beneficiary of his employer-issued life insurance policy, making her eligible to receive $112,000.