Tyler fired more than 16 rounds from his rifle - shooting at an employee standing outside and firing as he entered the store, blowing out the front windows, authorities said. He shot at five other workers in an aisle, killing Christine LoBrutto, 18, and Bryan Been, 24, Kaplan said.
"I do not believe that they were specifically targeted. I believe everybody in the store was a target," said Kaplan.
Tyler, who began working at the supermarket less than two weeks ago, drew his handgun and killed himself, the prosecutor said.
The motive was under investigation. But family members said Tyler had been discharged from the Marines two years ago after suffering from depression and had never gotten over his mother's death; the five-year anniversary was coming up next week, they said.
And on a Twitter account where he posted in 2009, with a photograph identified by family members as Tyler, he posted about hating Marine life.
"I'm starting to see why plp go on killin sprees," he wrote in October 2009, using the handle @Tylerbkstyle. And these m--f--- are reeeeeeally pushin my kill everyone I see button."
Tyler was discharged from the Marines in 2010 after just under two years in the service in Twentynine Palms, Calif., the Marines said. The infantryman from New York City never served overseas, said a Marine spokeswoman, Capt. Kendra Motz. She would not comment on the circumstances of his discharge.
A cousin, Shanteya Dyson, said Tyler had not been the same since his mother died of cancer. His father died when he was young.
"That was his best friend. He was always a quiet guy. But he got more quiet. He really didn't speak at all. He was just blank," said Dyson.