AURORA, Colo. (CBS4/AP) — Aurora police say one person has been arrested after several pipe bombs and bomb-making materials were found inside a home.

Spokeswoman Cassidee Carlson says police were responding to a small fire in a basement Tuesday when they found suspicious items, including illegal fireworks, apparent homemade explosive devices, and other bomb making materials.

“The home owner advised that there were additional pipe bombs in a shed in the back,” Carlson said in a statement.

Michael Grover, 55, is facing charges of possession of explosives and was being held in the Aurora jail initially on a $6,000 bond. Later in the day Grover’s bond was raised to $250,000 after more bombs were found. He lives with his wife and teenaged son.

Carlson says police got a search warrant to look for more dangerous materials and more pipe bombs were found, bringing the total to six to eight. They also found an unknown substance.

“It is my understanding from the bomb techs that dealt with these two pipe bombs is that they were pretty powerful devices,” Carlson said. “It could have possibly totally demolished the suspect’s house, and maybe caused some damage to neighboring houses.”

Four houses have been evacuated as a precaution.

Neighbors told CBS4 Grover would routinely set off fireworks in their neighborhood.

“He’s been kind of stocking up on the guns in case of the end of the world type thing,” neighbor Don Daniels said. “He was convinced on Dec. 21 we were going to be all finished.”

The explosives that have been found so far were taken to a safe area and detonated.

Grover is being held on a $250,000 bond.