Boise, Idaho: A man targeted children attending a three-year-old's birthday party during a stabbing spree that wounded nine people at an apartment complex in Idaho on Saturday night, police said.

The man, identified as Timmy Kinner, 30, had returned to the complex, Wylie Street Station Apartments, around 8.45pm on Saturday, a day after he was asked to leave, William L. Bones, the police chief in Boise, Idaho, said at a news conference on Sunday.

Kinner began attacking the children with a knife, said Bones, who was visibly emotional as he described a scene of victims scattered across the apartment complex, in the street and on the walkway.

Among the victims, he said, were the three-year-old who was celebrating her birthday, two four-year-olds, a six-year-old, an eight-year-old and a 12-year-old. The three other victims were adults who tried to intervene. Four victims received life-threatening injuries.

"This was an attack against those who are most vulnerable, our children," Bones said. "It's untenable, it's unconscionable. It's pure evil in my mind."