county fire chief investigators dennis johnson says many of the powerful illegal fireworks led to fire and injuries. cal fire staffed its lookout tower above mount hamiltono watch for fireworks activity while san jose police have numerous officers working overtime and will deploy special operations units. >> to go ahead and do selective enforcement in certain areas that have been traditionally hot spots during fourth of july where people are setting off illegal fireworks. >> robert honda, nbc, bay area news. >>> in san francisco, crews are preparing for tonight's big show along the waterfront. they are getting ready at pier 50. that's where workers are loading four barges with fireworks. the show will last 25 minutes and feature more than 5,000 fireworks, which are carefully positioned. >> we don't focus as much on the big stuff, because of the f word, so we try to keep things in the mid to lower range, so if that pesky fog rolls in, it doesn't obscure too much of the show. >> fire is the f word everyone is worried about in california. you can see the fireworks show from pier 49. the show starts at 9:30 tonight. it's one of 60 fireworks displays around t