Nassau police say they received nearly 500 complaints of illegal fireworks on the Fourth of July.
A total of 12 people were arrested and given appearance tickets in Nassau.
Officials also say at least two fires in Nassau County were started by firework debris not properly disposed of.
"Fireworks are illegal - fireworks are dangerous," says James Hickman, Nassau assistant chief fire marshal. "You don't know what you're getting. They're not professional grade, many of them are in haphazard factories elsewhere and shipped here just to make a dollar."
No arrests were made for illegal fireworks in Suffolk County, but police could not provide the number of firework-related complaints they received.