The mother of Aaron Alexis says she does not know why her son opened fire at the Washington Navy Yard, killing 12 people and is "so, so very sorry that this has happened."
Cathleen Alexis made the statement on Wednesday from her home in Brooklyn, New York.
"Aaron is now in a place where he can no longer do harm to anyone, and for that I am glad," Alexis said. "To the families of the victims, I am so so very sorry that this has happened. My heart is broken."
More from GlobalPost: 13 dead in shooting at US Navy Yard in Washington, DC (LIVE BLOG)
The gunman's mother did not take reporters' questions.
Authorities say the former Navy reservist was suffering from mental illness, including paranoia, and as recently as last month in Rhode Island had an incident which he complained to police about hearing voices.
On Wednesday, Defense Secretary Chuck Hagel announced the government would be reviewing security procedures at US defense installations.
"Obviously, when you go back in hindsight and look at all of this, there were some red flags," Hagel said. "Of course there were. And should we have picked them up? Why didn't we? How could we? All those questions need to be answered."
President Barack Obama is due to attend a memorial service Sunday for the 12 victims of the shooting.