The mother of the US man who killed 12 people in this week's shooting at a Navy complex in Washington says she is "so, so very sorry that this has happened."
Cathleen Alexis said Wednesday that she does not know why her son, Aaron, did what he did and she will never be able to ask him.
The mother read a statement at her home in New York. She concluded, "My heart is broken."
The 34-year-old Aaron Alexis opened fire Monday before he was killed in a shootout with police.
Authorities say he had been suffering several serious mental problems including paranoia and a sleep disorder.