At least two people have been killed and another two are missing after an explosion and fire at German chemical company BASF’s headquarters in Ludwigshafen.
Several more were injured in the blast.
BASF said the explosion had happened during work on a pipeline route for transporting raw chemicals to shipping.
Flames and a cloud of smoke could be seen in a harbour area in the north of the town, where oil and gas tankers supply the plant.
Residents were told to close their windows as the cloud of smoke spread.
The explosion happened at about 11:20 (09:20 GMT) on Monday.
BASF officials said the fire that caused the blast began in a supply line that transported flammable liquids and liquefied gas to a tank at the harbour. Police ruled out that the incident was caused by a terrorist attack, reports said.
Seven people were injured, six seriously. The company’s medical director said the situation was still confused and changing from minute to minute.
Several fires broke out after the blast and there were reports of some residents living close to the port having breathing difficulties. Officials later stressed there was no evidence of a risk to public health.
A pall of smoke rose about 100m (330ft) into the air and nearby towns and cities were all warned of potential hazards. Five hours after the incident, small fires were still burning in the area, although all were under control, officials said.
BASF manager Uwe Liebelt said the cause of the blast was not yet known but added that 14 facilities had been shut down. A separate explosion that happened three hours earlier in the nearby town of Lampertheim was not related, he said.
The BASF plant is the world’s biggest chemical complex. Among the facilities that were turned off were two steam crackers that make up the heart of its Ludwigshafen facility.
Steam is used to “crack” naphtha gas at the site, ultimately to make products such as ethylene, propylene and hydrogen.
Rhineland-Palatinate police warned motorists in the area to avoid the towns of Oppau, Edigheim and Pfingstweide.
Ludwigshafen fire: BASF blast hits German HQ