SAN ANTONIO (AP) — Officials say more than 20 freight cars have derailed in San Antonio in a weekend accident that left some loads of coal spilled.

Authorities say nobody was hurt and no hazardous materials were aboard the Union Pacific train during the derailment late Sunday afternoon.

Fire Department Battalion Chief Tony Rodriguez says authorities are trying to determine what caused the derailment in a rural area on the south side of San Antonio. Officials say cleanup is expected to take several days.

Messages left with Union Pacific weren't immediately returned Monday.