AURORA, Colo. - Aurora police allowed evacuated neighbors to return home Tuesday night after authorities removed several explosive devices and bomb-making materials from a house and shed.

Residents of several nearby houses, who were evacuated overnight as a precaution, were allowed to return home about 6:20 p.m. Tuesday, Aurora police said via Twitter.

Police said investigative crews will return about 9 a.m. Wednesday to continue working at the house on South Bahama Street and East Louisiana Street.

A bomb squad and a hazardous materials spent several hours Tuesday processing the home, the shed and surrounding grounds.

The explosive devices and bomb-making materials were found by firefighters responding to a small fire in the basement of the home around 10:30 p.m. Monday. 

The responding fire crew found fireworks, bomb-making materials and possible explosive devices so the Arapahoe County bomb squad was called in. Police said the bomb squad found pipe bombs in a shed behind the house.

Aurora police spokeswoman Sgt. Cassidee Carlson described the two pipe bombs as "pretty powerful devices" and said bomb techs had informed her they "could have possibly totally demolished the suspect's house and possibly damaged other houses."

"If his house would've went up, mine probably would've went up with it. And of course nobody wants that, so it's definitely scary," neighbor Donn Daniels said.

Carlson said officers arrested the homeowner, Michael Grover, on charges of possession of an explosive device.

On Tuesday afternoon, officers with a search warrant went into Grover's home. Inside, they found more devices.

"A few more devices were found inside. So bomb squad back in to remove devices," said a Tweet from Aurora Police.

While the bomb squad was in the home, they found an unknown liquid chemical, Carlson said.

A hazardous materials team was called in to check it out. They, in turn, called a special team from Buckley Air Force Base.

Police later said the chemical was not a "bio-threat" -- or biological threat -- but did not comment further.

Meanwhile, the bomb squad removed all explosive devices from the property.

"This is a slow process, we want to do it safely," said Carlson.

Carlson said officers are still trying to determine why Grover had so many devices.

"His motivation for making these homemade explosives and having those materials in his house is not clear to us," Carlson said, adding that it was something investigators would want to ask the suspect.