Two explosive devices found inside a home Monday were detonated at the Plum Creek Golf Course nearly 12 hours after police officers noticed dangerous chemicals at the house during an unrelated visit

Investigators said the devices were intentionally made and were just steps away from becoming bombs.

As police, firefighters and the bomb squad went the neighborhood, residents were forced out of their homes. People in more than 30 homes were evacuated and some spent the night at a Red Cross shelter set up at the Douglas County Fair Grounds. They were allowed to return early Tuesday morning.

Castle Rock police officers noticed dangerous chemicals inside the home on the 400 block of W. Prestwick Way just after 8 a.m. Monday. Police arrested two high school boys overnight for suspicious behavior in downtown Castle Rock. One of them lives at the house on Prestwick Way.

When officers went to inform the boy's parents he was arrested, they found the chemicals and decided they needed to take precautions including calling in the ATF and FBI.

“You see a yellow line across your street and evacuated, you want to make sure is that far enough? Is that safe enough?” said Kyle Freedman, a resident in the Plum Creek neighborhood.

“That’s very surprising. I had other guesses about what was going on but possible explosives wasn’t something that came into my mind. I’ve got two young boys and so that’s very concerning,” said neighbor Erin Maronick.

After the police officers discovered the chemicals, they called in Castle Rock Fire and Rescue and the Douglas County Bomb Squad.

“As the initial bomb squad technicians went through the house, they found a number of items, a number of other chemicals, things that looked suspicious,” said Sgt. Tim Ratcliff with the Castle Rock Police Department.

The items found inside the home were so concerning, the FBI and ATF were called in to take a closer look with their advanced equipment.

A hazmat decontamination area was set up near the home. It wasn’t until after the sun went down that FBI and ATF investigators went inside to see what the chemicals were. That’s when the found the two devices.

On Halloween night, neighborhood kids were expecting to dress up and get candy in the area, but even the youngest residents knew their holiday plans were changing.

“I think no more trick or treating for us until we actually find out what happened and who did it. But I think we can still trick or treat, just maybe go a little farther down that we usually do,” said 9-year-old Vin Maronick.

Investigators spent Monday night going through the home to see if any other chemicals or devices are there.

The Castle Rock police chief said there are possible criminal charges but said the investigation is still early and on-going.