VILNIUS, Lithuania (AP) — Powerful explosions were heard in the suburbs of Lithuania’s capital Wednesday morning after several rail cars loaded with liquefied gas caught fire, authorities said.

One person was injured, according to the fire and rescue department. Columns of smoke were visible across Vilnius and residents in the area were warned to stay indoors.

Interior Minister Vladislavas Kondratovičius told reporters initial information suggests that “the fire was most likely caused by a violation of occupational safety conditions, but all versions are being investigated.”

The carriages that caught fire belong to Polish company Orlen, police said.

The tankers were carrying liquefied petroleum gas from Orlen’s Lithuanian unit’s refinery to the Baltoji Vokė LPG terminal in Vilnius, the company said in an email. There was a fire, followed by an explosion, it said.

The terminal isn’t owned by Orlen’s Lithuanian unit and the logistics operation was carried out by a contractor, so the company is cooperating with authorities to investigate the cause, it said. “At this point there is no suspicion that this is the result of intentional actions,” it added.