PLAYAS DE ROSARITO, Mexico — Assaults on American tourists have brought hard times to hotels and restaurants that dot Mexican beaches just south of the border from San Diego.

Surfers and kayakers are frightened to hit the waters of the northern stretch of Mexico's Baja California peninsula, long popular as a weekend destination for U.S. tourists. Weddings have been canceled. Lobster joints a few steps from the Pacific were almost empty New Year's weekend, usually a busy time.

Americans have long tolerated shakedowns by police who boost salaries by pulling over motorists for alleged traffic violations, and tourists know parts of Baja are a hotbed of drug-related violence. But a handful of attacks by masked, armed bandits since summer — some who used flashing lights to appear like police — marks a new extreme that has spooked even longtime visitors.

Lori Hoffman, a San Diego-area emergency room nurse, said she was sexually assaulted Oct. 23 by two masked men in front of her boyfriend, San Diego Surfing Academy owner Pat Weber, who was forced to kneel at gunpoint for 45 minutes. They were at a campground with about 30 tents, some 200 miles south of the border.

The men shot out windows of the couple's trailer and forced their way inside, ransacked the cupboards and left with about $7,000 worth of gear, including computers, video equipment and a guitar.

Weber, who taught dozens of students in Mexico over the last 10 years, plans to surf abroad in Costa Rica, perhaps New Zealand. "No more Mexico," said Hoffman, who reported the attack to Mexican police. No arrests have been made.

The Baja California peninsula is known worldwide for clean and sparsely populated beaches, lobster and margaritas and blue waters visited by whales and dolphins. Surfers love the waves; fishermen go to catch tuna, yellowtail and marlin. Food and hotel prices are often hard to beat.

News of harrowing assaults against American tourists has begun to overshadow that appeal in the northern part of the peninsula, home to drug gangs and the seedy border city of Tijuana. The comparatively isolated southern tip, home to the tony Los Cabos resort, has remained safer and is still popular with Hollywood celebrities, fishermen and other foreign tourists.

Local media and surfing Web sites that trumpeted Baja in the past have reported several crimes that U.S. and Mexican officials consider credible. Longtime visitors are particularly wary of a toll road near the border that runs through Playas de Rosarito — a city also known by its English translation, Rosarito Beach.

In late November, as they returned from the Baja 1000 off-road race, a San Diego-area family was pulled over on the toll road by a car with flashing lights. Heavily armed men held the family hostage for two hours. They eventually were released but the bandits stole the family's truck.

Before dawn on Aug. 31, three surfers were carjacked on the same stretch of highway. Gunmen pulled them over in a car with flashing lights, forced them out of their vehicles and ordered one to kneel. They took the trucks, and left the surfers.

Aqua Adventures of San Diego scrapped its annual three-day kayak trip to scout for whales in January, ending a run of 10 years. Customers had already been complaining about longer waits to return to the U.S.; crime gave them another reason to stay away.

"People are just saying, 'No way.' They don't want to deal with the risk," said owner Jen Kleck, who has sponsored trips to Baja about five times a year but hasn't been since July.

Charles Smith, spokesman for the U.S. consulate in Tijuana, said the U.S. government has not found a widespread increase in attacks against Americans, but he acknowledged many crimes go unreported. The State Department has long warned motorists on Mexico's border to watch for people following them, though no new warnings have been issued.

Mexican officials acknowledge crime has threatened a lifeblood of Baja's economy. In Playas de Rosarito, a city of 130,000, police were forced to surrender their weapons last month for testing to determine links to any crimes. Heavily armed men have patrolled City Hall since a failed assassination attempt on the new police chief left one officer dead.

"We cannot minimize what's happening to public safety," said Oscar Escobedo Carignan, Baja's secretary of tourism. "We're going to impose order. ... We're indignant about what's happening."

Tourists visited Baja about 18 million times in 2007, down from 21 million the previous year, Escobedo said. Hotel occupancy dropped about 5 percentage points to 53 percent.

In the city's Puerto Nuevo tourist enclave, which offers $20 lobster dinners and $1 margaritas, restaurant managers said sales were down as much as 80 percent from last year. One Saturday afternoon in October, masked bandits wielding pistols walked the streets and kidnapped two men — an American and a Spanish citizen — who were later released unharmed. Two people who were with them were shot and wounded.

Omar Armendariz, who manages a Puerto Nuevo lobster restaurant, is counting on the new state and city governments to make tourists feel safer. He has never seen fewer visitors in his nine years on the job.

"It's dead," he said.