Detectives discovered the fireworks after acting on a tip. The fireworks have a street value of about $20,000, according to the L.A. County Sheriff's Department.
L.A. County firefighters are keeping the fireworks in an undisclosed location. After the holiday, the fireworks will be taken out of state and destroyed.
According to state fire officials, around 40,000 pounds of illegal fireworks are confiscated in California every year. L.A. County leads the state with an average of 30,000 pounds confiscated annually. They are not of the so-called "safe and sane" variety.
"'Safe and sane' don't shoot up in the air, and they don't explode. All of these [illegal fireworks] do, and they're extremely dangerous, they're fire hazards and [can cause] personal injury," said L.A. County Fire Inspector Keith Wood.
The "safe and sane" firework stands are now popping up. Even though they are legal where they are sold, local fire departments are asking people to take precautions to avoid injuries and property damage.
L.A. County Fire is encouraging residents to celebrate the holiday by attending a public fireworks display.
"They have trained professionals there, they have a safety perimeter set up, and the show is set up in such a way that they're going to minimize the potential for any type of fires to start [and] injuries to happen to the public," said Tony Imbrenda with L.A. County Fire.
One such local firework show will be held at the Rose Bowl. Pasadena Fire has spread fire retardant around the Rose Bowl in anticipation of the show. For tips on how to be safe this Fourth of July and where to watch fireworks in L.A. County, visit the L.A. County Fire Department's Safe July 4th website.