The woman was struck in the crosswalk at 1st and M streets in Southeast early Wednesday afternoon.
"The initial indications are that she was in the crosswalk," D.C. Police Lt. Nicholas Bruehl says.
It's not known if the woman had the walk signal at the time, Bruehl says.
Police say the driver of the dump truck kept going until other drivers told him he'd hit someone.
The driver returned to the scene and is cooperating with police.
Bruehl says charges against the driver are pending.
WTOP's Neal Augenstein is covering this story. Follow him on Twitter.
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