Liberty Island was reopened Friday about four hours after a 911 caller threatened to blow up the Statue of Liberty, forcing visitors to evacuate and emergency responders to swarm in, authorities said.

The all clear came about 3 p.m., said the NYPD, which sent its bomb squad, harbor units and emergency services to help federal authorities investigate.

A 911 caller had threatened to blow up Lady Liberty, and the National Park Service put all visitors and employees onto ferries shortly after being alerted about 11 a.m., said park service spokeswoman Mindi Rambo.

At one point, two U.S. park police dogs alerted their handlers they found something near lockers at the base of the Statue of Liberty, she said.

Details on what they had found were not immediately available.

The threat sent visitors and park workers streaming onto ferriers back to Manhattan, while ferries headed part way out to the park and Ellis Island had to return to the terminal, where passengers waited in long lines to receive refunds.

A passenger aboard a Statue Cruises vessel reported never making it to Liberty Island and being on the water for about an hour before making the trip back.

Statue Crusies issued a statement saying it transported about 2,700 people from the island and offered them all refunds. The company said it was working with parks officials to reunite them with their belongings. Service to Liberty Island is scheduled to resume at 8:30 a.m. Saturday.