The subway rail that snapped and caused a train to derail, injuring 19 passengers and stranding hundreds underground, had been installed just weeks before the accident, the Metropolitan Transit Authority said Saturday.

The rail that broke under a train in Queens on Friday morning was manufactured in the U.S. in November and installed in March. The other rails from that shipment will be tracked down and inspected, according to the MTA.

The cause of the derailment, the most significant in years on the nation's largest subway system, remains under investigation.

The express F train was heading for Manhattan and Brooklyn when six of its eight cars derailed around 10:30 a.m. more than 1,000 feet from the nearest station. - AP