An alleged narcotics dealer tossed a handful of deadly fentanyl powder at a cop investigating a Bronx drug packaging mill, authorities said Thursday.

Members of the New York Organized Crime Drug Enforcement Strike Force burst into 304 Willis Ave. with a search warrant on November 7.

They found seven alleged dealers in the apartment surrounded by a large quantity of heroin and fentanyl packaged into 20,000 single-dose glassine envelopes stamped with the “HBO” logo.

As the authorities tried to secure the apartment, Christian Rojas grabbed a handful of loose powder and flung it in a cop’s face.

“The officer exhibited fentanyl-related symptoms, including nausea and shortness of breath and was treated by emergency responders,” the city’s Office of the Special Narcotics Prosecutor said in a statement.

Another officer was sickened by the airborne powder and briefly lost consciousness, officials said. Two additional cops became ill from inhaling the dangerous substance.

The seven alleged dealers — Christian Rojas, Nassar Lacewell, Francisco Payano, Mario Guerreo, Jose Gonzalez, Freddy Roja and Margaret Payano — were indicted on charges of criminal possession of a controlled substance and criminally using drug paraphernalia. They’re scheduled to be arraigned Thursday in Manhattan Supreme Court.

Rojas, who is being held on $150,000 cash or bond, faces an additional six counts of assault, attempted aggravated assault upon a police officer and reckless endangerment.