Washington (CNN) U.S. law enforcement officials are boosting security measures ahead of the Fourth of July holiday, authorities said Tuesday.

More police are being deployed to prominent locations because of concerns of terrorist threats, including some from suspected ISIS supporters in the U.S. who may heed the group's call to carry out attacks.

The FBI, Department of Homeland Security and National Counterterrorism Center relayed their concern in a bulletin last Friday that listed the holiday weekend and several upcoming Prophet Mohammed drawing events scheduled in the coming weeks as possible targets for attacks.

The New York Police Department said its "enhanced counterterrorism and security measures" will be greater this Fourth of July than in past years.

The Los Angeles Police Department is similarly increasing security measures. Michael Downing, the LAPD's counterterrorism chief, said the concern is that many of the extremists being watched by law enforcement are "looking for an excuse to go operational."