Five Haitian children and a young woman being smuggled into the United States drowned yesterday after they were forced off a boat at gunpoint a half-mile from the South Florida shore, authorities said.

Some of the bodies were found in the shark-inhabited Atlantic near Lantana Beach. Apparently the operators of the 28-foot cabin cruiser forced them off in hope of avoiding capture.

"They threw some of the children out first to make the adults go into the water after them," said Sue Sullivan, director of the Haitian Affairs Office of the National Council of Churches.

"They fired shotguns over the heads of the others to force them into the water," said Sullivan, who based her description on interviews with the survivors.

Two men were arrested and charged with six counts of first-degree murder in the predawn drownings. U.S. Immigration and Naturalization Service officials identified them as Jeffrey Robert Hastings, 29, of Hypoluxo, Fla., and James J. Knowles, 18, of Tarpon Bay, the Bahamas.

The boat owner, John W. Ferguson, 36, of Delray Beach, Fla., was released.

Ten other Haitians forced off the boat came ashore at Manalapan, Fla., INS officials said. They were given first aid and blankets, and later held as material witnesses at a detention facility in Delray Beach, about 50 miles north of Miami. The lone woman among them was being held at Palm Beach County jail.

Two Haitians were unaccounted for, INS and Delray Beach police said they are believed to have reached shore and gone into hiding.

The drownings are the latest in a series of events to befall Haitians seeking to flee economic hardship and alleged political persecution.

Twenty-three Haitian men, women and children drowned a year ago after their overcrowded boat capsized near Freeport, the Bahamas. Last January, 19 Haitian men drowned near Andros Island in the Bahamas when their skimpy craft capsized.

INS officials and Haitian supporters said that yesterday's incident was the first in memory in which Haitians - who started fleeing to South Florida shores in greater numbers in 1972 - died as a result of being forced into the water at gunpoint.

"This is a really sad, terrible situation," said Bettye Wiggs, a spokesman for the Haitian Refugee Center in Miami. She expressed satisfaction with the speedy arrests.

Haitians normally pay $500 to $1,000 each to be smuggled to the United States aboard boats, Wiggs said. Many have been forced off the boats before reaching their destination, she said, but they were usually deposited on land.

"We have many cases of people being dropped off on somebody's island and being told that they were in Miami when they were nowhere near Miami," Wiggs said.

In interviews with wire services yesterday, Palm Beach County Sheriff Richard Wille said the smugglers apparently forced their human cargo, who reportedly had paid to $550 each, overboard after being scared by a police car spotlight on shore.

"Apparently, the man who was running the boat fired shots in the air and told the Haitians to jump overboard," Willie said. CAPTION: Picture, Divers and sheriff's deputies surround bodies of three Haitian children pulled from the sea at Manalapan, Fla. AP