A shelter-in-place order was issued in Milpitas on Tuesday morning and lasted most of the day as authorities searched for suspected bomb-making equipment stashed at the home of a man with a criminal past, police said.
SWAT and bomb squad personnel wrapped up the scene Tuesday evening after a nine-hour investigation in which they examined and carefully removed chemicals and other matierials from the home.
Investigators have not removed all of the chemicals from the home and will return to the scene Wednesday morning, police said. No major evacuations will happen, but the homes on both sides of the house will have to be cleared as a precaution, they said.
Investigators quickly ruled out a possible meth lab but not explosives, and they still were not certain what the materials were intended for.
"The chemicals in and of themselves are not necessarily dangerous, however if someone knew what they were doing they could combine them to create something potentially dangerous," Milpitas police spokesman Sgt. Bryan Hinkley said.
The shelter-in-place mandate, which began about 9 a.m., was lifted about 6 p.m. Tuesday. It was issued for residents living on View Drive between Spring Valley Lane and North Temple Drive. View Drive, which had been closed to traffic, was reopened.
Neighbors told NBC Bay Area they've seen smoke coming from under the garage door every night. They've also heard popping, percolating sounds like a huge coffee maker.
For weeks, neighbors said, they smelled sulfur and other chemicals. Many neighbors have been concerned for their family and children. The biggest fear: Many thought the house could blow up.
Authorities obtained a search warrant to examine the house that was believed to be housing hazardous chemicals that could potentially be used to construct an explosive device, police said.
"The search warrant is to see if there is bomb-making equipment inside or if there had been bomb-making materials inside or if there is information on how to make bombs," Hinkley said.
SWAT teams on Tuesday cleared the home, which housed a man, a woman and two children, police said. The man was detained and questioned, but he was not arrested and is cooperating with investigators.
"The person that we have detained that's associated with the chemicals, he does have a criminal history," Hinkley said. "However, none of it is related to terrorists, terrorism, bomb making equipment, bomb making or any other illegal activity associated with chemicals."
Neighbors originally notified police a few weeks ago that chemical smells were emanating from the house.
"We've actually had one fire just down this street or the following street," neighbor Jason Morningstar said. "So it could be a tinderbox if something were to go off like that."
Fire and police officials later located chemical containers outside of the residence and then contacted an agency asking whether or not the discovered chemicals could be used in a dangerous manner. Confirmation from the outside agency led to the authorization of the search warrant, which was handed down by a Santa Clara County judge.
Milpitas police said the investigation is ongoing, and an officer was to remain stationed on View Drive overnight. There are no public safety concerns at this time, police said.