“He is someone who used to listen to my sermons, my talks here,” said Mustafa Kuko, director of the Islamic Center of Riverside. “I sat up last night thinking about him and what’s happened.”

Kuko has trouble understanding how Farook could have betrayed the very principles of his religion. “We’re told in Islam if you take one human life, it’s as if you’ve taken all of mankind.”

Farook, 28, and Tashfeen Malik, 27, his wife and mother of his 6-month-old daughter, were killed in a shootout with police after the couple opened fire at the Inland Regional Center social services agency in the city of San Bernardino, killing 14 people.

Mahmood Nadvi, an assistant imam at the Dar Al Uloom Al Islamiyah-Amer mosque in San Bernardino, which Farook began attending in 2014, was equally disturbed. “You can’t be a true Muslim and sleep after this,” he said “We weep for our brothers and sisters lost in humanity.”