Carrying signs reading "Navy Out!", fishermen and protesters in nine speedboats invaded restricted waters off of Vieques Island Saturday, stalling U.S. Navy bombing exercises that have drawn the criticism of residents and politicians.

Reporters watched from a boat outside of restricted waters as the speedboats raced toward the Navy's firing range, passing within 500 feet of several amphibious personnel carriers that were shuttling equipment and marines to a beach in preparation for mock invasion exercises. Two warships were about 3 miles away.

Although security ships chased the boats out of the restricted waters, the fishermen managed to pull up to the range and drop a group of protesters off, three of whom were detained by authorities. The boat chase stalled ship-to-shore shelling for about three hours.

Anti-Navy activists said at least 19 people were hiding on the range but Navy spokeswoman Lt. Cmdr. Katherine Goode said the Navy was "confident the range was clear" and that bombing exercises had resumed.

"They are continually putting the lives of protesters at risk," said Robert Rabin, an anti-Navy activist. "They have been lucky and we have been lucky that no one has gotten killed."

Since this round of exercises began Thursday, at least 28 people have been detained for allegedly trespassing on federal property.

"This is a war that we have had with them for 60 years," said Jose Garcia, a 39-year-old fisherman. "My grandfather, father and my uncle all fought the same war and the Navy hasn't been able to put us down. The fishermen are the biggest headaches that they have."

The fishermen, who say the waters around the bombing range are rich with conch, lobster and red snapper, are prohibited from fishing in the restricted areas during the Navy exercises. Fishing is among the most important sources of income on Vieques.

The Navy recently announced a program of compensation that would pay fishermen $100 for each day that bombing exercises prevent them working, and grants of up to $25,000 to start small businesses.

But some say it's not enough.

"This is to make them know that this island and these waters are ours," said Carlos Maldonado, a 25-year-old fisherman, before he joined Saturday's protests. "They have to leave."

The latest Vieques exercises started four days after 70 percent of Vieques residents voted for an immediate end to the bombing in a nonbinding local referendum Sunday. Thirty percent supported the Navy remaining indefinitely and resuming live bombing. President George Bush has promised the Navy will leave by 2003. But only 1.7 percent of voters among Vieques' 9,100 residents backed his plan.

The exercises, expected to last 10 days, involve ship-to-shore shelling, air-to-ground bombing and beach landings with 23,000 personnel, making the maneuvers some of the biggest since a civilian guard was killed by off-target bombs in 1999, when the Navy began using inert bombs.

The bombing is conducted 4 miles from civilian areas.