When deputies saw a van leaving the house, they stopped and searched it, finding about $10,000 worth of illegal fireworks.
Deputies then called explosives investigators and L.A. County firefighters to the house and conducted a search, finding boxes of illegal fireworks stacked to the ceiling in several rooms.
"The house has a minimal amount of furniture inside and has boxes stacked within each room and has some food in the kitchen as though it was definitely rented to be a stash house," said Sgt. Chris Romash of the L.A. County Sheriff's Department.
Authorities said those fireworks were worth an estimated $500,000.
The fire department removed two large truckloads of fireworks from the house. Officials said the devices could have sparked a devastating fire.
"The potential in this home was outstanding," said Inspector Fredrick Stowers of L.A. County Fire. "It's a tribute to the fact that they had done such good police work to be able to notify us so that we can get these things out of the community."
Two 22-year-old men were taken into custody, and they face charges for illegal possession of fireworks.
Illegal-fireworks sales have plagued La Puente for years. The city is spending thousands of dollars to try to stop it.
"We're not going to tolerate illegal fireworks here in our city," said city manager Josefina Kenline.
La Puente allows legal fireworks, but some say it's time to ban all fireworks.
"I believe that legal fireworks mask the ability for law enforcement to locate and arrest those that are using illegal fireworks," said councilmember Vince House.
Fire officials remind the public that fireworks are illegal in L.A. County. Those who want to enjoy fireworks can attend the many fireworks shows available at various locations.