US marks July 4 amid worries over security, sharks and wildfires

New York: Millions of Americans readied on Saturday for Independence Day parades and firework shows amid worries over possible security threats, a spike in shark attacks on East Coast beaches and the danger of wildfires in the West.

The Department of Homeland Security and the Federal Bureau of Investigation have issued an alert asking local authorities and the public to remain vigilant for possible threats following recent calls for violence by Islamic State leaders.

New York Governor Andrew Cuomo ordered increased monitoring statewide for the holiday weekend under the direction of the New York Division of Homeland Security and Emergency Services.

In New York City, the nation's biggest police force assigned about 7,000 officers and nearly all its counterterrorism personnel to handle security around Independence Day events.

"We're constantly seeking to be creative, to be proactive and not just be preparing to respond if something happens," New York Police Commissioner Bill Bratton said this week. "The name of the game is to prevent it."

Hundreds of thousands of people were expected to flood the National Mall in Washington, D.C., for a parade, concerts, and a fireworks display that uses 6,500 shells. The National Park Service is installing 3.4 miles (5.47 km) of chain link fencing, 14,000 feet (4,270 meters) of bike racks and almost 350 portable toilets to cope with the crowds.

Washington was shaken on Thursday by an unfounded report of gunshots at the Navy Yard military base, a report that sparked a massive law enforcement response. Police Chief Cathy Lanier told reporters police were in a heightened posture ahead of the holiday.

"When we talk to our residents and visitors who want to celebrate Independence Day in the District of Columbia, it should be very clear to everybody that we take clear and credible threats or calls from our citizens and employees very, very seriously," Lanier said.

On the US West Coast, which is already battling wildfires, communities in Washington state and Oregon restricted or banned fireworks out of fear that the dazzling displays of pyrotechnics would spark fresh blazes. Cupertino, California, and Anchorage, Alaska's largest city, canceled fireworks show because of such concerns.

Revelers celebrating the holiday on the beaches of North Carolina, meanwhile, were warned by the National Park Service to use extra caution after an unprecedented surge in shark attacks.

The seven attacks recorded in the state by midday Thursday have already surpassed the previous high of four in 2014, according to the International Shark Attack File. While the news will keep some people from venturing into the water, others won't give up the surf, said shark file curator George Burgess.

"There are those who have made their decision: 'I don't care. I'm going to go in the water no matter what,'" he said. Celebrations in Texas feature country music legend Willie Nelson, and in Oklahoma, a watermelon seed spitting contest.

Nelson's all-day picnic, held this year at the Circuit of the Americas racetrack outside Austin, typically draws tens of thousands of people for a day of drinking, music and frequently an illegal substance often associated with the Texas musician.

Meanwhile in Oklahoma, the "Watermelon Seed Spittin' World Championship" gets underway in Pauls Valley, about 60 miles (100 km) southeast of Oklahoma City. The record spit to beat is 66 feet, 11 inches (20.41 meters), set in 1989 by Jack Dietz of Chicago, organizers said.