At least two people died and six were severely injured on Monday in an explosion and fire at chemicals maker BASF's biggest production site in Germany, the company said.
Two people are still missing, BASF said.
The explosion occurred on a supply line connecting a harbor and a tank depot on the Ludwigshafen site at around 1120 local time (0920 GMT), according to BASF, the world's biggest chemicals company.
A fire that broke out following the blast sent up plumes of smoke for hours, prompting BASF and the city of Ludwigshafen to urge residents in the surrounding area to avoid going outside and to keep their windows and doors shut.
Measurements taken in the area so far have indicated no risk from toxic fumes, BASF said.
"We deeply regret that employees died and several people were injured. Our sympathy is with the affected people and their families," the Ludwigshafen site's chief, Uwe Liebelt, said in a statement.
The company said it was unclear so far what caused the explosion. BASF also said it could not say what financial impact the explosion might have.
It shut down 14 facilities, including its two steam crackers, large units that make basic chemical components, for safety reasons and because the supply of raw materials was disrupted by the blast.
The Ludwigshafen site, around 80 kilometers (50 miles) south of Frankfurt, is the world's largest chemical complex, covering an area of 10 square kilometers (four square miles) and employing 39,000 workers, according to BASF. It is located on the Rhine river and receives many of its raw materials by ship.
The harbor at which the explosion occurred is a terminal for combustible fluids such as naphtha and methanol that are important for BASF's supply of raw materials.
News of the explosion came less than two hours after BASF said four people were injured in a gas explosion at its Lampertheim facility, a plant near Ludwigshafen that makes additives for plastics.
=========== One worker dies following explosion and large fire at BASF By PRW
Photo by @Jaaanik/Twitter Residents near the plant had apparently been advised to keep windows and doors shut.
A BASF worker has died following an explosion and fire at the German chemical giant's facility in Ludwigshafen.
Initial reports had quoted the German chemicals giant as saying the fire followed an explosion, the cause of which had not been determined, which took place at a riverside harbour.
It then confirmed that an explosion at at the North Harbor during work on a pipeline, which resulted in fires. Several people were injured, and some were reported missing.
In the latest update, BASF confirmed an employee had died.
"According to the latest information we have, one person died as a result of today’s fire in the North Harbor at BASF in Ludwigshafen," the group said.
Six people had suffered serious injuries, several others received light injuries, it added. The injured were being treated in local hospitals.
Six other people were still missing.
“We are deeply saddened that one employee has died and several have been injured. Our deepest sympathy lies with the affected people and their families,” said Uwe Liebelt, BASF site manager Ludwigshafen.
Logistics employees and truck drivers were evacuated at Gate 15 and brought to a safe location in the Ebert Hall, the firm said.
"Gate 15 is closed. Gate 3 is currently not manned and therefore closed to vehicular traffic. The turnstiles are available as well as all other gates. The normal shift change will happen as planned.
"There is visible smoke. The surrounding towns are recommending to residents in the affected areas of Ludwigshafen and Mannheim, until further notice, to stay indoors and close doors and windows," it added.
BASF and the City of Ludwigshafen held a press conference at 16:00 local time, and the chemicals firm said more information would follow.
Photos on social media showed a thick plume of smoke rising from the fire site.
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Cause of deadly explosion at BASF chemical plant in Ludwigshafen remains unclear
Investigators in the western German town of Ludwigshafen are still trying to determine the cause of the explosion at the BASF chemical plant. Two people were killed, one remains missing and six were severely injured.
Following the severe explosion at the BASF chemical plant in Ludwigshafen on Monday, German authorities continued on Tuesday to investigate the cause of the blast which killed at least two people. Officials said terrorism has been ruled out.
At a press conference on Tuesday afternoon, Ludwigshafen fire service chief Peter Friedrich said fire services had not yet been able to reach the site of the accident.
"There's still a thick layer of foam on the pipeline where the explosion happened," Friedrich said, adding that the pipes would have to cool down before the site can be accessed.
Employees still missing
The two people known to have died in the accident were both members of BASF's own fire brigade.
One person, thought also to be a member of the fire service, was still unaccounted for on Tuesday, while another six people remained in intensive care. Fire Chief Friedrich said the missing person is believed to be in the harbor. Divers, however, hadn't yet been able to enter the waters. A second person, who earlier in the day had also been reported as missing, has since been identified at a local hospital where they were receiving treatment.
The explosion and fire on Monday occurred at around 11:30 a.m. local time (0930 UTC) at a river harbor, used to unload flammable liquids and liquid gas.
It took firefighters 10 hours to extinguish the resulting blaze. During the incident, BASF was forced to shut down 20 facilities, including two steam crackers, which produce basic hydrocarbon chemicals used to manufacture a wide range of plastics and other chemicals.
Following the explosion, a pipeline that was undergoing repairs began spewing soot, BASF plant manager Uwe Liebelt told reporters. Several witnesses also posted videos on social media in which huge flames and plumes of thick black smoke were seen billowing from the plant.
The city of Ludwigshafen reported on Twitter that residents located near the plant were complaining of "respiratory irritation."
BASF confirmed at Tuesday's press conference that the substances that burned in the subsequent blaze included ethylene - used in producing solvents and insulation - and propylene, used in producing car paint and adhesives.
A day on since the explosion, residents in Ludwigshafen and the nearby city of Mannheim were told by authorities to continue to keep all doors and windows closed. No increases of harmful substances had been reported, however.
Damage levels unclear
As a safety precaution, BASF also shut down 14 other production plants on Monday and erected water barriers between the northern inland port and the Rhine.
The economic consequences and the damage levels remain unclear.
The incident on Monday came just two years after Ludwigshafen was shaken by a devastating gas explosion, close to the BASF chemical plant. Gas transport company Gascade had been digging around a buried pipeline at the time of the blast. One excavation worker was killed and 20 other people were injured. Nearby houses and trees were burned to charcoal, leaving an entire neighborhood devastated.
Authorities in Ludwigshafen have shared a telephone hotline for those directly affected by Monday's explosion: +49 62 157 086 000.