Police in Ludwigshafen, Germany, are continuing to investigate the cause of a deadly gas explosion near BASF's main production site at Ludwigshafen that killed a construction worker and injured at least four other workers seriously on October 23.

The blast occurred as workers employed by contractor Gascade, a Kassel, Germany-based joint venture of BASF and Russian gas giant Gazprom, were attempting to dig down to a line buried around two meters below nearby apartment blocks.

Gascade said it was unclear what had damaged the pipe, a section of a 57-kilometer line that supplies manufacturing companies and leads southward to the city of Karlsruhe.

The explosion set off several fires, which destroyed around 80 parked cars and threatened residential neighborhoods. Local reports said about 60 homes were damaged, with about two-thirds of them no longer inhabitable.

Gascade has a pipeline network extending around 2,400 kilometers through Germany, including some that connect to the Nord Stream pipeline running beneath the Baltic Sea and connects Germany with Russia.

Opponents of the CO pipeline planned by Bayer MaterialScience between Dormagen and Uerdingen used the Ludwigshafen blast to again criticize Bayer's plans for the pipeline, which has been held up by protest for several years.