RALEIGH, North Carolina: A major US port was shut down Tuesday after nine containers of “highly explosive material” were accidentally punctured, officials said, urging that part of the city be evacuated.

The accident happened around 4:45 a.m. (0945 GMT) when a forklift punctured the imported containers during offloading, Morehead City Mayor Jerry Jones said.

The chemical involved was pentaerythritol tetranitrate, known as PETN, he said, adding it was “highly explosive, but not airborne.”

PETN, which can be used in detonators and grenades, is the same material that was used in the botched Christmas Day bombing of a Northwest airliner en route from Amsterdam to Detroit.

“We have found highly explosive material in nine containers at Morehead City Port,” Amy Thompson, a police official at the city’s port division, told AFP earlier.

“The material was found in an accidental puncture. When they punctured it they realized that it was explosive material.” Authorities reported there were no injuries and no damage to the environment.

But Julie Naegelen, who works in downtown Morehead City for the Cataret County Chamber of Commerce, told AFP she and her colleagues noticed an odor outside early Tuesday.

“We started to smell something, that smelled like it was burning. We really don’t know if it was related in any way,” Naegelen said.

Shortly after seeing Homeland Security vehicles drive down the street, Naegelen and her colleagues decided to evacuate their offices.

Mayor Jones said the voluntary evacuation area spread over a half-mile radius of downtown Morehead City, which has a population of some 9,500 people. Police also closed a stretch of highway 70 near the port.

The port, one of the deepest on the US East Coast, routinely handles dangerous cargo, the mayor said.

“We are an international port. We get a lot of hazardous materials coming through Morehead City,” he said.

Jones said cleaning up the site would pose special risks. “You’ve got to have a nonfriction shovel - something that will not create a spark,” he said.

PETN is used as plastic explosive and also to treat heart conditions. By itself it is non-explosive, but can detonate easily if mixed with other materials.

The port, which lies just four miles (seven kilometers) from the Atlantic Ocean, is one of the deepest on the US east coast, and according to its website is a major exporter of phosphates.

It handles both breakbulk and bulk cargo and is the second largest importer in the country for natural rubber.

US officials have charged a young Nigerian, Umar Farouk Abdulmutallab, 23, with trying to use PETN as a weapon of mass destruction onboard Flight 253 from Amsterdam on Christmas Day.

The explosives failed to detonate correctly but caused an onboard fire as the plane approached Detroit, burning Abdulmutallab. He has pleaded not guilty to six charges arising out of the incident.

Richard Reid, the “shoe bomber,” also tried to detonate a PETN device on an American Airlines jet to Miami in 2001. And in 2009 a man tried to assassinate a member of the Saudi royal family by hiding a PETN-based bomb inside his body.