WASHINGTON -

Federal regulators say they've issued an emergency order requiring tests of crude oil before shipment by rail in response to a string of train explosions and fires since last summer.
    
The Federal Railroad Administration said Tuesday it also is prohibiting shipping oil using the least-protective packing requirements.
    
The order is a response to derailments of trains carrying oil from the Bakken region in North Dakota and Montana that resulted in explosions and fire, including a train that exploded in Lac-Megantic, Quebec, near the U.S. border, in July, killing 47 people.
    
Shippers already had to classify oil shipments based on their risk for explosion or fire, but federal investigators found that many shipments were being misclassified as less dangerous. The order requires testing for classification before shipment.