Investigators believe at least one of the suspects in the STEM School Highlands Ranch shooting on Tuesday stole the guns from the parents of the 18-year-old suspect, two sources with knowledge of the investigation told Contact7 Investigates on Wednesday.

Douglas County Sheriff Tony Spurlock confirmed at a news conference Wednesday morning that at least two handguns were used in the shooting. High-ranking sources told Denver7 Tuesday night that three handguns and a rifle were recovered, but said the rifle was not used in the shooting.

Spurlock said at the news conference that investigators were working with the federal Bureau of Alcohol, Tobacco, Firearms and Explosives to determine how the suspects, an 18-year-old male and a juvenile female, obtained the weapons. He said at the time it was “too early to tell” if the suspects had assistance in obtaining the weapons.

The sources said Wednesday that they believe the parents of Devon Erickson, the 18-year-old suspect, bought the weapons legally. Denver7 cannot say whether the parents had the guns secured inside the home.

People under age 21 are not allowed to buy handguns in Colorado.

Read more at thedenverchannel.com.