John Lu of Walnut had just sat down to dinner with his wife and three sons when a small, silver pistol appeared at his head.
"Shhh, we won't hurt you," said one man, his face covered with a knit mask.
Another robber waved a gun, yelling: "Scream and I'll blow your heads off."
The group of six robbers, who were believed to be ethnic Chinese from Vietnam, tied up each member of Lu's family with video cables and ransacked the house for half an hour. When they were finished, they walked out with $15,000 in jewelry and cash.
"I never thought this could happen here," said Lu, who survived decades of war in his native Vietnam only to be threatened at gunpoint in the quiet, sprawling suburb of Walnut. "I guess no matter where you move, they will follow."
Since the early 1980s, roving bands of Southeast Asian youths have robbed dozens of Asian families in the ethnic centers of Monterey Park, Chinatown and Westminster in Orange County.
But in the past year and a half, this rare and violent crime has spread to the pastel-colored residential tracts in the outlying areas of the San Gabriel Valley.
Law enforcement officials in suburban communities that have seen dramatic increases in their Asian populations in the last five years, such as Arcadia, Hacienda Heights, Walnut and Diamond Bar, have recorded at least 55 Asian-on-Asian residential robberies since the beginning of 1988.
Except in Monterey Park, Alhambra and Hacienda Heights, no residential robberies occurred in any of those cities before that date.
Unlike a burglary, which occurs when the occupants of a house are not present, a residential robbery is committed when residents are held up in their homes. Police say the crime is virtually unheard of except in drug disputes or the occasional case of a burglar who unintentionally enters an occupied house.
The San Gabriel Valley has become one of the hottest targets in the country for Asian gangs who have committed more than 100 robberies here, including the 63 in Monterey Park.
In contrast, police in Los Angeles and San Francisco estimate they investigate about 25 cases a year. San Jose, which has one of the largest Vietnamese populations in the state, reported 26 cases since the beginning of 1988.
"The San Gabriel Valley is right at the top of the list," said Monterey Park Police Capt. Joseph Santoro. "As the wave of people moves outward, so goes the crime wave."
But crime has become widespread in the Asian community because of the tradition of many immigrants of keeping valuables at home and the fear of retribution if they cooperate with police.
The robbers have targeted neither the richest nor the poorest, police say, but have struck with a randomness that has left a sharp-edged paranoia in its wake.
"Robbery has become the crime of the Southeast Asians," said Detective Ben Lee of the Los Angeles Police Department's Asian Task Force. "You cannot move away from it. The problem will follow wherever you go."
The robbery of the Lu family on the night of May 21, 1988, was the first to occur in Walnut, a booming city of tract homes on the eastern fringe of Los Angeles County, where 20% of the population is Asian.
The robbers entered the house through an open side window shortly after 9 p.m. and appeared as the family was eating dinner in the kitchen.
They spoke to the family in English, but used Chinese among themselves. Lu believes that they were ethnic Chinese from northern Vietnam because of their accent.
The robbers took cash, checks, gold, video cameras, electronic equipment and even a wedding ring, although the robbers gave it back Lu's wife before they fled.
'She Wants to Leave'
"My mother used to look so young," said Lu's teen-age son, Paul. "She wants to leave now. She wants a place with security guards."
The crime of residential robbery by Asian gangs was virtually non-existent in the United States eight or nine years ago and has spread with surprising speed.
The first cases occurred in Monterey Park in the early 1980s. Within a few years, Westminster, in the heart of Orange County's Vietnamese community, and Los Angeles were seeing their first cases.
The crime is now surfacing in such cities as Houston, Seattle, San Jose and San Diego.
Law enforcement officials say the gangs have established a loose association of contacts in dozens of cities, making it extremely difficult to track and arrest gang members.
"What we've seen in the last two or three years is the establishment of a network," Santoro said. "They may be in the San Gabriel Valley one day, but the next day they're in Houston. What do you do?"
Sgt. Steve Brennan, head of the Los Angeles County Sheriff Department's robbery and assault investigations in the Hacienda Heights area, said: "They come in and go out. How do you stop them? How do you stop lightning?"