Twenty-four hours after a huge blaze broke out at a fireworks factory, killing a firefighter, injuring 17 other people and destroying at least 20 houses, hundreds of Danish firefighters finally contained the fire Thursday.

As many as 350 buildings — private homes and small businesses — may have been damaged by the fire at the N.P. Johnsens (search) fireworks factory in Kolding in western Denmark (search).

Television footage showed some of the 20 homes burned down but authorities said the powerful explosions and thick smoke had damaged many nearby houses.

The blaze was thought to have started Wednesday when two containers with fireworks were being loaded onto a truck, police said. It was unclear what caused the containers to combust.

"We're still keeping a large area cordoned off," said police spokeswoman Gitte Schou. "There are still three containers filled with fireworks in the middle of the burning factory and there is a risk of explosion."

"Firemen are trying to cool the containers down but there is still a tremendous heat," she added. "It might take days before people can return to their homes."

The fire at the factory in Kolding, 200 kilometres west of the capital, Copenhagen, started Wednesday shortly after 2 p.m. and quickly spread to a nearby building, leading to a chain reaction of explosions.

Although the plant has a licence to store 300 tonnes of fireworks, police said they believed that as many as 2,000 tonnes were stockpiled.

Bendt Bendtsen, Denmark's economics and trade minister, said "there was a suspicion that the factory had violated fireworks storage rules."

A 33-year-old firefighter was killed and 17 people, including firemen, rescue workers and police officers, had been treated for minor burns and smoke inhalation, Schou said. All had been released from hospital. Overnight, some 60 people had been under medical observation after complaining about respiratory problems.

Teams of psychologists counselled people affected by the accident.

About 2,000 people living near the factory were evacuated to nearby schools and seniors homes as authorities set up a security perimeter around the area.

In wake of a May 2000 explosion of a firework storage depot in the Dutch town of Enschede (search) that killed 22 people, several neighbours of the plant in Kolding demanded that it be shut down.