A third child was wounded and remains in a critical condition in hospital.
Police Lt. Matt Murray says it appears to have been an isolated shooting and that the killer is not thought to be at large.
More top news
More than a million adults in the UK may have been wrongly diagnosed with asthma, according to an NHS watchdog.
A whisky advert featuring David Beckham has been cleared by the advertising regulator.
Councils will have to cut money from services such as libraries because of the rising cost of caring for the elderly, a new report warns.