BALTIMORE, AUG. 20 -- Each month for seven months, an off-duty Miami firefighter dutifully made the run up I-95 from Miami to Baltimore, federal agents said, dropping off a kilo of high quality cocaine. Street value: $400,000.

Usually he drove a rental car, they said, a common practice among couriers. He would turn it in here and fly back to Miami, they said.

Then last spring, agents said, when the courier began to feel the heat of "Operation Pipeline," a joint highway surveillance program by East Coast state police, he switched over to Amtrak and started riding the rails instead.

But on April 2, after being spotted by Amtrak police as a possible suspect and kept under surveillance for the 23-hour Miami-to-Baltimore run, the firefighter, identified as Harry Franklin Payne, 30, was arrested as he alighted from the train here and charged with possession of cocaine with intent to distribute.

His arrest led to more indictments today. Two other Miami firefighters, including a lieutenant, plus a civilian suspect, were charged with a variety of counts, breaking up what the Drug Enforcement Administration says was a small but tightly run network of cocaine suppliers for Baltimore.

"They were taking $400,000 out of the Baltimore economy every month," said DEA spokesman Bob O'Leary. "That's money for food, for rent, for alimony, whatever."

The three men indicted in federal court in Miami today are fire Lt. Nathaniel Dennis, 34; Firefighter Larry Deleveaux, 29, and civilian Rudolph Jackson, 28. All were charged with conspiracy and possession of cocaine with intent to distribute.

Dennis and Deleveaux were arrested about 7:30 a.m. today, but Jackson was reported still at large. Payne is currently free on bond awaiting trial.

O'Leary said Dennis and Deleveaux obtained the drug from undisclosed sources in Miami and "contracted with Payne" to deliver it to Baltimore. Jackson, the civilian, who lives in Miami but "has connections in Baltimore," would distribute the cocaine once Payne brought it to Baltimore, O'Leary said.