birthday looks like any other 4th of july so far. there are parades in towns and cities across the country; watermelon eating contests like this one in davie, florida; and celebrations of the nation's liberty. but the signs are also plain to see that this 4th is marked by heightened concern about a possible terror attack. while the intelligence community has not pointed to any specific credible threats, the many gatherings on this holiday packed with national symbolism have police on high alert. here's david begnaud. >> reporter: in new york city tonight, law enforcement is sending out a united message: if you dare to do harm, we're ready for you. >> we need to be here tonight. >> reporter: n.y.p.d. commissioner bill bratton says the department is worried about lone wolf attacks. >> well, we have... we have increasing concerns, as you are aware, over the last several months, of the inspired threat