By Jeanette Rundquist and Tomás Dinges/The Star-Ledger

SANDY HOOK — The Coast Guard will release more information at 10 a.m. today on its investigation into a possible mayday call hoax which set off a massive response involving dozens of rescue vehicles and hundreds of emergency personnel.

At 4:20 p.m. Monday, the Coast Guard received a frantic mayday call. The call was brief — about 30 seconds — but the details specific: There had been an explosion aboard a yacht called the Blind Date, 17 miles off the coast of Sandy Hook. According to the Coast Guard, the male caller said the vessel had sunk, but all 21 people on board had made it to life rafts. The crew was unable to send a GPS positioning because the vessel had lost power, the caller said.

At least seven people were injured, the caller told the Coast Guard. A good Samaritan sailing vessel was aiding the injured, the Coast Guard said.

The call set off a response that brought dozens of rescue vehicles, state police medevac helicopters and 200 emergency personnel from all over New Jersey, and as far away as Long Island and Cape Cod, to the Monmouth County shore. At sea, Coast Guard helicopters furiously searched the ocean waters for wreckage and survivors.

But five hours after that initial call, the search had turned up nothing.

No boat. No people. No debris. No signal from an emergency beacon, which would have activated upon hitting water.

By nightfall, rescue crews were sent home and the search was suspended.

"The investigation has begun into whether or not this was a hoax," Coast Guard spokesman Erik Swanson said shortly after 9 p.m. Monday night. "The search has been suspended pending further information that leads us to believe there is a real emergency."

Coast Guard Lt. Joe Klinker said the initial report had to be taken seriously.

"We had a pretty clear transmission reporting there had been an explosion with injuries, the vessel was taking on water and that a number of persons had abandoned ship into life rafts and that there were multiple unspecified injures," he said. "Our protocol is to treat this as a legitimate distress."

The unit that received the call, "felt there was enough veracity ... that they should get someone out there," Klinker said.

John Warren, a spokesman for the Gateway National Recreation Area, said that early Monday evening the Coast Guard had said nine people were confirmed injured, and asked park officials to help arrange transportation for them to area hospitals.

At one point, at least six medevac helicopters, 15 ambulances and two medical buses were waiting at the shoreline, most at the Fort Hancock area within Sandy Hook. But by 7 p.m., the helicopters activated their rotors and flew away. Most of the waiting ambulances were officially released and left the scene, turning into a caravan that crept down the length of the Hook.

"Basically, there are no patients coming," said John Grembowiec, the New Jersey EMS Task Force leader from the scene.

In a statement Monday night, the Coast Guard said making a false distress call is a federal felony with a maximum penalty of five to 10 years in prison, a $250,000 fine and reimbursement to the Coast Guard for the cost of performing the search.

In addition to being a federal crime, the Coast Guard said, false distress calls "waste taxpayer dollars, put Coast Guard and other first responders at unnecessary risk and can interfere with the Coast Guard’s ability to respond to actual distress at sea."

Monday’s search included two Coast Guard boat crews and four Coast Guard helicopter crews, which searched approximately 638 square nautical miles, the statement said.

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"More than 200 first responders assembled mass casualty receptions areas in Newark, and Coast Guard Station Sandy Hook, preparing to receive the reported injured passengers," said Cmdr. Kenneth Pierro, of Coast Guard Sector New York.

The Coast Guard offers a reward of up to $1,000 for information leading to the arrest and prosecution of anyone responsible for making a false distress or hoax call to the U.S. Coast Guard. Anyone with information regarding false distress calls is encouraged to anonymously contact the U.S. Coast Guard Investigative Service at (646) 872-5774 or (212) 668-7048.

At marinas and restaurants around Sandy Hook, speculation was rampant Monday about what was happening.

"I heard about it, but we didn’t see it. We didn’t see any smoke or fireball out there. We saw ambulances, flashing lights, but that’s all," said Steve Mehler, manager at Bahrs Landing restaurant in Highlands, which is just across the Shrewsbury River from Sandy Hook.

"I believe it happened (but) maybe it didn’t. I don’t know," Mehler said. "All those firetrucks and ambulances and emergency vehicles, they would not be out there if something didnt’ happen.

"It’s not even funny," he said. "It’s kind of serious."

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According to its statement, the Coast Guard and other state and local agencies responded to more than 60 suspected hoax calls in the northern New Jersey, New York City and Hudson River region in 2011, according to the statement.

Last June in Sandy Hook Bay, the Coast Guard and several agencies spent 10 hours searching for a 33-foot sailboat named Courtney Lynn and four passengers after a man called on VHF Channel 16 saying he was taking on water. The call turned out to be false.

Other agencies have also fallen victim to hoaxes.

In 2010, an anonymous caller told the State Police that three men with guns jumped out of a black passenger van at a New Jersey Turnpike rest stop. Troopers surrounded the vehicle and ordered the passengers, a group of teenagers from Queens, out one by one at gun point. The troopers didn’t find any weapons, and the incident sparked racial profiling allegations,

Three months later, investigators tracked the 911 call to the cell phone of Rodney Tanzymore, a passenger in the van. He was eventually charged with creating a false public alarm and sentenced to three years probation.

A similar emergency call also caused panic in New Brunswick in December of 2009, when local police received a tip that someone had planted a bomb in the city’s train station. Transit investigators quickly determined the incident was a hoax, and arrested Russel P. Gardner, 45, for the false bomb threat.

Star-Ledger staff writers Tom Haydon, Brian Donohue and James Queally contributed to this report.

Related coverage:

• Was it a hoax? Report of Sandy Hook boat explosion not yet confirmed

• Boat explosion reported off coast of Sandy Hook

• Reports of sinking sailboat at Sandy Hook a possible hoax, officials say



• Possible Wyckoff hostage situation turns out to be hoax

• Ex-newspaper driver convicted of terrorism hoax after mailing boss envelope with white powder