A man went on a stabbing spree at a toddler's birthday party at a low-income apartment complex for refugees in the US state of Idaho, wounding nine people including six children, police said on Sunday. The attack was apparently motivated by revenge after the man, identified by police as Timmy Kinner, 30, of Los Angeles, was asked to leave the residence in the state capital Boise on Friday. He was not a refugee himself but had been staying with an acquaintance for a few days, police chief Bill Bones told a news conference. He then returned on Saturday night to "exact vengeance", first targeting the children attending a three-year-old's birthday party, then the adults who tried to protect them. The children ranged in age from three to 12 years old. Four of the victims had life-threatening wounds, but police did not specify how many of these were children or adults. "It appears from the investigation, it was a matter of where they lived, not a matter if they knew the suspect," Mr Bones said. Most of the refugees in the complex are from Syria, Iraq and Ethiopia. Kinner, who has been charged with nine counts of aggravated battery and six counts of injuring a child, had previously been convicted for numerous crimes and served prison time in Kentucky, said Mr Bones. Boise, in the south-western corner of the western state, has a population of about 220,000. The state of Idaho has a small but growing immigrant population, accounting for about 6 per cent of the total. Immigrants make up some 40 per cent of the labour force in the farming and fishing sectors. On Saturday, several thousand people marched outside the Idaho State Capitol in Boise to protest the immigration policies of President Donald Trump's administration, one of many such rallies across the country.