25-year-old Joseph Tuono, of Millsboro, has been on the run since the incident late Tuesday night.
It was around 11:30 p.m. when the 23-year-old air marshal from West Orange, New Jersey, contacted Delaware State Police to say she was driving behind a car was being driven erratically on Long Neck Road in Long Neck, Del.
The car pulled into the Pot Nets Coveside development in Long Neck and Tuono got out, approached the woman, and allegedly began shouting obscenities are her.
The woman identified herself as an air marshal, police say, and Tuono tried to get back in his vehicle. The air marshal tried to restrain him, and was struck a number of times in the abdomen.
Police say Tuono then fled into a marsh and has not been seen since.
Anyone with information on Tuono's whereabouts is asked to call Delaware State Police at 302-644-5020.