MIAMI (AP) _ Three men in a speedboat dumped a ton of cocaine overboard Thursday, then tried to ram the pursuing Customs boat until agents' gunfire forced them to surrender.

Customs agents retrieved 34 duffel bags containing about 2,000 pounds of cocaine from the water off the Upper Keys, said Kitty Pryor, spokeswoman for the Miami office of the U.S. Customs Service.

The retail value of the cocaine was about $30 million, officials said.

Those figures could go higher, said Ms. Pryor, because Customs and Coast Guard agents were still searching the area for any wayward duffel bags.

A Customs patrol boat, part of the anti-drug Operation Blue Lightning, spotted the 32-foot Bertram, equipped with two 350-horsepower engines for extra speed, east of the Alligator Reef Light in the Upper Florida Keys about 3 a.m., Ms. Pryor said.

When the men aboard the Bertram saw the Customs boat's blue light, they sped off, tossing duffel bags overboard as they fled, Ms. Pryor said.

After the duffel bags had been dumped, the Bertram's driver rammed the Customs boat, Ms. Pryor said.

''The bad-guy boat attempted to ram our boat,'' said Charlie Jordan, chief of the Key Largo Customs office. ''That happened a number of times, so there was no choice. Our guys fired a bunch of shots into the stern (of the Bertram).''

The men aboard the Bertram then surrendered, he said.

Arrested on charges of assaulting a federal officer, smuggling, conspiracy to smuggle and possession of an illegal substance with intent to distribute were Francisco Francisco Morales, 38, of Miami Beach; Domingo Fernandez, 27, of Pompano Beach, and Luis Gustavo Gualdado, 33, of Miami.

The men were turned over to the U.S. Drug Enforcement Administration and were scheduled to be brought before a federal magistrate Friday.

The nearly 2,000-pound seizure ranks as one of the largest seizures ever. The largest on record was 3,906 pounds taken by Customs in 1982 from a Colombian jet at Miami International Airport.

Later Thursday, approximately $6.4 million worth of marijuana and a 60-foot vessel were seized by the Coast Guard just north of Dry Tortugas, according to Coast Guard Petty Officer Joe Dye.

Coast Guard officers aboard the Navy hydrofoil Hercules boarded the Sally Ann at about 11 a.m. and discovered approximately 16,000 pounds of marijuana on board. Three Cuban U.S. residents and one Cuban alien were arrested, Dye said.