BEIRUT (Reuters) - A large fire erupted on Thursday at Beirut port, sending a huge column of smoke above the city a little more than a month after a massive blast devastated the port and surrounding residential area of the Lebanese capital.

The blaze erupted in the shattered duty free zone of the port and one official said it was limited to that area. But it jangled nerves in a nation grappling with a deep economic crisis that has posed the biggest threat to Lebanon’s stability since its 1975-1990 civil war.

The army said a store of oil and tires had burst into flames, although it said the cause was not immediately clear.

Television footage showed an army helicopter dropping water on the fire.

The head of civil defense told Lebanon’s AlJadeed television it was not certain what materials were burning. But he urged residents to stay calm, saying the fire was contained to one place.

There were no immediate reports of injuries but some residents drove out of the city, still traumatized by the Aug. 4 blast that killed about 190 people.

“I am forced to get them out of Beirut from the smoke and the fire that is happening at the port again,” said Majed Hassanein, 49, who was taking his wife and two children by car.

He said his son was still suffering shock from the blast that ruined a swathe of capital near the port and shattered windows across the city. About 6,000 people were injured in the explosion and about 300,000 left without inhabitable homes.

The head of Lebanon’s Red Cross, George Kettaneh, said there was no fear of another explosion as a result of Thursday’s fire and there were no injuries, although he said there were some people suffering from shortness of breath as a result.

Television footage showed firefighters trying to douse the blaze in an area surrounded by the mangled remains of warehouses that were destroyed in the explosion last month.

That blast was caused by a huge store of ammonium nitrate that had been kept at the port in poor condition for years.