Police investigators who track youth gangs in Montgomery County said yesterday they were surprised by the number of Korean youths involved in a fight Thursday night that left one teen-ager dead, and said they know of no organized gang activity in the Korean community.

But they said the fight fits the same pattern of other gang-related incidents in Montgomery County that have grown in number and become increasingly more violent in recent months.

"What upsets me is the seriousness of the injuries and the increasing number of weapons involved in these fights," said George E. Hackey Jr., a county police officer who tracks gang activities.

Hackey said he knew of no loosely organized youth gangs in the Korean community similar to gangs that exist in other neighborhoods.

"They tend to really stick to themselves, so maybe no one has come forward yet to identify the gangs like they have in other communities," he said. "It's something we have to look into."

With a reputation for good schools, well-manicured lawns and posh shopping malls, Montgomery County is an unlikely backdrop for gang warfare. But in the last two years, six youth gangs have staked out turf here, according to police.

The gangs, made up mainly of juveniles and known by such menacing names as the Young Assassins, have been responsible for numerous fights, assaults, robberies and, in at least once instance, a murder for hire, according to police.

The Ghostbusters, the largest and oldest, was formed by youths from Lincoln Park in Rockville sometime last summer, he said. The Soldiers, the second largest gang, is made up of youths from Emory Grove, a community on the outskirts of Gaithersburg.

The third largest, and considered the fastest growing, is a Wheaton gang called TKO. A smaller Aspen Hill gang, known as the Young Assassins, is a recent spinoff of TKO, police said.

Another gang from the Sandy Spring area calls itself The Young and the Restless, and a spillover gang of District and Prince George's County youths is known as the Gangster Chronicles, Hackey said.

"In the 1960s, we had those kinds of rivalries where everybody took pride in their school. But this is totally different. It's not the level of the sophisticated Chicago street gang, but the potential is there," he said.

The first gang-related incidents in the latest wave of activity occurred in late 1983. Youths from the District, known as the A-Team, robbed students and caused fights at local school dances and sporting events, police said.

"We suddenly started getting reports of the A-Team showing up all over the county. We think young people in these neighborhoods organized themselves to defend against the A-Team," said Hackey.

A "rumble" at Lake Forest Mall in December involving 150 rival Ghostbusters and Soldiers convinced police that the level of gang violence was serious and growing. Two officers were injured in the melee, and for the first time a handgun was among the weapons confiscated, Hackey said.

In February, a 25-year-old Kensington man was beaten to death by three suspected members of the Young Assassins in what police described as a murder for hire. It was the county's first gang-related death, police said.

A 16-year-old youth has been charged with second-degree murder in the case, said Arlene O'Donnell, a detective in the youth division.

County Executive Charles Gilchrist has since formed a special task force to deal with the problem, said O'Donnell.