Authorities are investigating why Washington police officers weren't sent to provide backup for firefighters en route to a woman who had been armed with a knife on a previous call.

Police say the woman was again armed with a knife or pair of scissors when firefighters arrived at her Northeast Washington home early Tuesday. After police arrived, the woman was arrested and charged with assaulting a firefighter. No one was injured.

Police spokeswoman Margarita Mikhaylova says there had been a miscommunication. She says the police supervisor did not know the firefighter had referenced a possible weapon in the call he made while en route.

Police said in a statement that the woman had called 911 about a dozen times over 24 hours, each time refusing assistance from authorities.