Images broadcast by local media showed flames illuminating the night sky, but officials say there have been no injuries caused by the explosion."According to the initial assessment, we do not see any malign cause, but the investigation will cover all possible options," Amber Grid chief executive Nemunas Biknius told reporters.Mr Biknius said the pipeline - which was built in 1978 - had undergone some recent maintenance work, and that officials would try to establish whether that had contributed to the blast.The mayor of Pasvalys district, Gintautas Geguzinskas, told LRT that he didn't have any concrete information on the cause of the blast, but said that local residents had told him "they saw some work being done near the pipeline where the explosion happened".Meanwhile, the BNS news agency reported that officials had decided to evacuate the nearby village of Valakelie."