The false distress call about a yacht exploding off Sandy Hook, N.J., which prompted an extensive search costing hundreds of thousands of dollars, came from a radio line in New Jersey or southern New York, authorities said Tuesday.

The antenna that picked it up was in Highlands, N.J., U.S. Coast Guard officials said.

NBC 4 New York has learned that the FBI in New Jersey is investigating the hoax along with the Coast Guard.

Capt. Gregory P. Hitchen theorized at a briefing Tuesday that the hoax, described as the agency’s largest in recent memory because of the massive response it drew, was orchestrated for nothing more than attention.

“People like the attention they can cause by watching the helicopters and boats go out and actively search,” he said. “It’s pretty strange.”

The multiagency mission was launched after authorities received an emergency radio transmission around 4:20 p.m. Monday from a boat identifying itself as the Blind Date. The caller, who described himself as the captain in the 20-second call, reported the boat was 17 nautical miles east of Sandy Hook.

“We have 21 souls on board, 20 in the water right now. I have three deceased on board, nine injured because of the explosion we’ve had… I’m going to stay by the radio as long as I can before I have to go overboard,” the caller says in the audio clip released by the Coast Guard Tuesday.

“This person was somewhat calm but was giving us a convincing story,” Hitchen said.

But Coast Guard crews and New York City police helicopters found no sign of any people or any distress in the water, and after two hours of searching it became increasingly clear there was no explosion.

The Coast Guard is offering a $3,000 reward for the prosecution of the person who made the call.

About three hours into the operation, emergency crews began leaving the mass casualty staging areas that had been set up to receive the reported injured passengers, and nearly five hours after the distress call was received the Coast Guard confirmed it was likely a hoax.

Officials are working through a list of boats named Blind Date as part of the investigation.

Hitchen said the public “should be very concerned that this person who perpetrated this hoax put the public at risk and put your first responders at risk.”

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. The Coast Guard and other state and local agencies responded to more than 60 suspected hoax calls last year in the northern New Jersey, New York City and Hudson River region.

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