Washington, Feb 17 (IANS): A train carrying crude oil derailed in the US state of West Virginia Monday, causing a massive explosion and an oil spill, as a state of emergency was declared in two counties of the state, media reported.

A home was destroyed in the accident, but there were no reports of injuries, CNN said, citing Lawrence Messina, spokesman for the West Virginia department of military affairs and public safety.

Nearly 30 of over 100 cars the train came off the tracks, the spokesman said. It was, however, still unclear what caused the derailment, which happened around 1.30 p.m.

Oil from the train spilled into the Kanawha river, a source of drinking water for residents in the Kanawha and Fayette counties of the state. West Virginia Governor Earl Ray Tomblin issued a state of emergency for both those counties Monday night. Residents have been urged to conserve water.

Police have also asked residents within a half a mile (nearly 1 km) of the accident site to evacuate until further notice.

"We've had some severe winter weather conditions here with significant snowfall. We don't yet know whether that's a factor in this (accident)," Messina said.