Warsaw, 11 p.m. The silence of the night is broken by the sound of roaring engines. For three years, night rallies have been held in city streets at speeds that frequently exceed 200 kilometers per hour.

Extreme sports have been popular among young people for many years. But night rallies add a new element of danger to an already risky sport. Flying lessons and bungee jumping, very popular until recently, no longer provide that true adrenaline rush that only breaking the law and outwitting the police can deliver.

"Individuals inclined to extreme sports seek stimuli they cannot find in everyday life," said psychologist Dr. Adam Sobolewski from the Warsaw School of Social Psychology. "People who race down city streets and put themselves and others in danger are as hungry for stimuli as skydivers. However, the former are predisposed to break social and legal norms because of their situations at home. It is a question of upbringing and respect for others."

Night riders form small, hermetic groups. They meet late in the evening at the end of the week. If a stranger approaches, they disperse instantly. The police know the most popular rally sites, which are wide streets outside the downtown area. In Warsaw, these are Toruńska Expressway (mainly in Annopol), Armii Krajowej Expressway around the Military Cemetery in Powązki, Wólka Węglowa, Dolina Służewiecka and Rosoła and KEN streets in Ursynów.

"Prevention is our primary goal," said Maj. Wojciech Pasieczny, an expert from the Road Traffic Department of the Warsaw Police Headquarters. "We cannot arrest people for gathering in groups. First and foremost we try to prevent rally organization."

Statistics concerning road traffic in Poland are disturbing. Last year, more than 51,000 accidents occurred on Polish roads, causing 5,640 fatalities and nearly 64,000 injuries. In the first six months of this year alone, 668 accidents were reported in Warsaw. Among almost 16,000 minor accidents, 23.4 percent resulted from speeding. Seventeen people were killed and over 200 injured. No separate statistics are available for night riders.

In the press the riders claim that they have not been involved in any serious accidents. They choose routes far from heavy traffic. That, however, by no means ensures safety. Piotr Wróblewski, a rally driver who has managed a rally driving school for nine years in Warsaw, says, "Drivers who are not active in auto sports on an everyday basis should not, in fact, drive fast at all. At 60 kph, they are unable to handle the basic maneuvers to deal with an emergency situation on the road. Above 100 kph, a sudden jerk of the steering wheel (to avoid an obstacle) results in an instant loss of control."

Night riders are usually young people with access to good cars who try to impress their friends. But the group also includes persons who it seems would be free of the need to impress: managers, employees of ad agencies, people with high and responsible posts. They drive at insane speeds at dawn, when city streets are empty. There are friendly garages where mechanics intervene in the event of an accident without drawing unwanted attention. The riders themselves say this is how they vent stress after a week at work. "It is rather about pursuing a different kind of stress," said Sobolewski. "The pressure they feel in their jobs is static. Their response to it is to find stress resulting from a real, dynamic and immediate danger."

The rallies came into fashion three years ago and the fad is spreading rapidly. "The media is largely to blame because it shows various celebrities who drive cars at high speeds," said Piaseczny. "Officially, nobody accepts it, but the message from the press and TV gets across."

Recently, the phenomenon has taken on an even more disturbing dimension as movies documenting races become available online. In the past few weeks one hit clip documented a night race through Warsaw. The amateur filmmakers recorded some of their excesses in the city center, on streets with regular car traffic. The title of one episode speaks for itself: Through Downtown Warsaw in 90 Seconds. Internet forums feature descriptions of rides at insane speeds, often in broad daylight and on crowded streets, when other drivers are shoved off the road. "In cases like that, excuses like 'we pose no threat, since we drive when the streets are empty,' just don't apply," said Sobolewski. "These lunatics have to realize they are a real, extreme danger to themselves and others. This is not a question of stretching the law to its limits, but purely criminal conduct."