Officials shut down a busy port and urged people to get out of town Tuesday after a forklift operator accidentally punctured containers of PETN, the highly explosive substance used in a Christmas Day airline bombing attempt.

Port police knew the shipment of pentaerythritol tetranitrate was coming from overseas and had extra security in place, Morehead City Fire Chief Wes Lail said. He would not say who imported the chemical or where it came from. U.S. Coast Guard Chief Petty Officer Mike Hvozda said the ship's last port of call was in Spain, but he was not sure what city.

No injuries were reported and officials did not count how many people left. The port remained closed late Tuesday afternoon.

PETN was part of a device authorities say a Nigerian man used to try to bring down a Detroit-bound Northwest flight on Christmas Day. It is often used in military explosives and found inside blasting caps. It is also the primary ingredient in detonating cords used for industrial explosions.

A company called Maxam UEB shipped the PETN, said Karen Fox, a spokeswoman for the North Carolina State Ports Authority, but she did not know where in the U.S. it was headed.

According to business directories, Maxam is an explosives manufacturer based in the town of Galdakao, near Bilbao, in Spain's northern Basque country.

That is according to various business directories. The company's web site is down, though the small portion that does come up also identifies it as an explosives manufacturer.

Morehead City Mayor Jerry Jones said the damage appeared to be an accident and there were no concerns about terrorism. He said a dock worker punctured the containers as he was unloading them.

Lail said nine containers were damaged and a small amount of PETN leaked out. He described the material as "slurry," part liquid and part solid. Hvozda said the material was shipped in cardboard drums that were about 2 feet high and 1 foot in diameter.

The spill happened at the mouth of a shipping container, and some material spilled onto the dock. The material was supposed to be unloaded before 8 a.m., the start of normal business hours at the port.

This is the first time in two years PETN has come into Morehead City, and the shipment was approved by the Coast Guard, Lail said.

Lail said crews were working on a six-step process to clean up the spill. By Tuesday afternoon, it had been contained and hazardous materials teams were cleaning it up and repackaging the broken barrels.

They had hoped to lift the evacuation recommendation by afternoon, but did not expect to meet that deadline. He would not speculate on when police might reopen roads and waterways around the port.

"Today is our goal," he said.

After the spill was reported just before 5 a.m. Tuesday, police told people near the port to stay away from windows and doors. Officers were sent downtown to knock on doors and relay alert and evacuation recommendations.

The Morehead port is one of the deepest on the East coast. Its Web site says its top import last year was sulfur products and the top export was phosphate.

The port is one of two in North Carolina and handled 1.8 million tons of cargo in 2009. The Morehead port employs 58 people who handled 118 ships and 415 barges in fiscal year 2009.

People in the town of 8,800 went about their business Tuesday afternoon, but there were indications the city was handling a potential disaster: A digital sign at the civic center detailed road closures and the streets near the port were deserted. Many people living within a half mile of the port left. Businesses were dark except for their neon signs.

Brian Fowler, a building contractor, said he let his crew of six go after officials recommended people leave.

"We didn't want to put our employees in harm's way," said Fowler, a lifelong Morehead City resident. He stayed for a meeting at a massive beach house his company is building, but did not plan to stick around long.

"They want us to leave, we are not going to hang out over here," Fowler said.