VIEQUES, Puerto Rico (AP) -- Protesters on two small boats fired flares at a U.S. Navy helicopter during training exercises off the Puerto Rican island of Vieques on Thursday, the Navy said. The SH-3 Sea King helicopter was pursuing the boats in a restricted area off the island when someone fired what appeared to be two marine flares at the helicopter, said Lt. Cmdr. Katherine Goode, a Navy spokeswoman. The flares missed, and no one was hurt, Goode said. Military officials detected the boats as they crossed into a restricted area, and the boats fled from the helicopter, a Coast Guard cutter and a police patrol boat sent to intercept them, Goode said. No one was reported arrested. The Navy has used a bombing range on the eastern tip of Vieques for six decades, training sailors for conflicts from World War II to the Persian Gulf War. Opponents say the bombardment harms the environment and health of Vieques' 9,100 residents, which the Navy denies. Hundreds of protesters have been arrested for trespassing on the firing range since 1999, when errant bombs killed a Puerto Rican security guard on the range. President George W. Bush said earlier this year that the Navy should end its training on Vieques by May 2003, but a bill recently approved by the House would require the Navy to stay until a suitable replacement is found. Protests against the exercises have waned since the September 11 terrorist attacks in the United States. Most protest groups agreed not to invade Navy lands during the current exercises, which began September 24. But some disagreed with the decision. Activist Aleida Encarnacion said the two boats had at least six protesters on them and that her husband, anti-Navy activist Carlos Zenon, had directed the protest action. Meanwhile, about 200 Vieques residents held a protest march to demand the Navy's withdrawal from Vieques. The march was held as part of a one-day-strike called by opponents of the Navy bombing exercises. The strike partially halted work in businesses, government agencies and schools.