"There is still so much, too much, to sort out about the tragedy in Aurora, Colo.," Boehner said in the weekly Republican media address. "Words cannot capture the horror, or make sense of something so senseless. So I won't try."
He said "when confronted with evil we cannot comprehend, Americans pull together and embrace our national family more tightly."
The shootings occurred in an Aurora movie theater where the latest Batman movie "The Dark Knight Rises" was opening in a midnight screening Friday morning. Suspect, James Holmes, 24, was in custody and police said they believe he acted alone.
"We join President Obama in sending condolences and prayers to the loved ones of those who were killed and wounded. And we all say 'thank God' for the police, the first responders, the doctors and the nurses whose swift and heroic efforts saved lives," Boehner said.
He said the "depth of our grief also reveals the depth of our love and resolve."
"Scripture tells us that the faith that sustains us is 'the substance of things hoped for and the evidence of things not seen,'" Boehner said. "We may not yet see or fathom comfort for the mourning, but we'll stand by them and we'll stand together, as one nation, in the difficult hours that lie ahead."