MEDELLIN, COLOMBIA -- A record tide of violence here -- including 1,200 murders in the first two months of this year -- has been sparked by feuding drug gangs, vigilante justice groups, cocaine cartel wars and personal vendettas, civilian and military authorities say.

"It is very difficult to definitively interpret what is happening in Medellin," said President Cesar Gaviria at a press conference March 1. "In part, there are changes in the power structure of the criminal organizations that operate there, but I do not think that is the sole cause of what is going on in Medellin. . . . It transcends drug trafficking, and it will take a relatively long time to secure public order there."

Medellin is one of the most violent cities in the world because of the cocaine cartel centered here. Following the declaration in July of a truce by the Extraditables, as leaders of the Medellin cartel call themselves, the murder rate dropped to nine per day. With the surrender of three top leaders of the cartel in December and January, many people expected the violence here to fade away.

But as control over armed groups began to disintegrate, discipline broke down and the murder rate jumped to 20 a day. In contrast, the murder rate in the District of Columbia, with half the population of Medellin, was slightly more than one per day last year, when there were a record 483 slayings.

Violence also is rising sharply in normally tranquil Cali, center of the rival Cali cartel, and narcotics experts believe some of the killing is due to fighting between the two groups. Friday night, 12 people were gunned down in three separate incidents.

Government, military and private groups agree on three primary factors generating the violence, all fueled to some extent by cocaine money: turf fights among gangs following the surrender of the top drug barons and the police killing of leaders of cartel boss Pablo Escobar's military operation; war between the police and the hired cartel killers; and armed groups seeking to "cleanse" society for ideological reasons.

"Cocaine money is the gasoline that fueled the fire," said a government official. "We lose more people there in a month than the allies lost in the {Persian} Gulf War, but we are not able to apply Patriot missiles or smart bombs to achieve victory."

Medellin, with 1.8 million people, is the industrial center of Colombia and is known for its temperate climate and orchid cultivation. Much of the city is relatively untouched by the violence, most of which takes place in the slums ringing the downtown area.

Sergio Estarita, a Medellin spokesman, said 1,200 violent deaths had been reported in the city in the first two months of the year. He said most of the victims were men aged 16 to 28, killed by gunfire. Human rights workers say the actual number of victims is actually higher because many killings are never reported.

In 1990, according to police figures, 4,637 people were murdered in Medellin, up from 4,141 in 1989.

While there have been short periods, such as in April, when killings surged to as many as 40 a day, this is the longest period over which the number of homicides has averaged as high as 20 a day, said Maria Emma Mejia, presidential counselor for Medellin.

Besides gang feuds, groups calling themselves "Robocop" and "The Friendly Group of Medellin" carry out "social cleansings" by killing suspected drug addicts and beggars and have taken responsibility for a series of multiple homicides.

In the first 59 days of the year, Medellin witnessed 15 "massacres," officially defined as killings with three or more victims.

The most shocking to the community occurred within the last two weeks. On Feb. 26 at about 7 p.m., nine young men playing soccer were gunned down on a small concrete court by masked men on motorcycles in the Tricentenario neighborhood. Five hours later, five more people in the nearby La Floresta neighborhood, including a 14-year-old girl, were taken from their homes, lined up against a wall and shot by four men dressed in military uniforms who rode in a black jeep.

Anonymous callers to local radio stations took responsibility for the actions in the name of Robocop, without further explanation.

Two days later, the Rev. Javier Tobon, a parish priest in the poor and violent Northeast community, made public a letter from The Friendly Group of Medellin, distributed to priests in the area with orders that it be read at all Sunday Masses.

"We alert all parents and the community in general to talk to their children, to stop them from smoking marijuana and crack and using chemical substances," said the communique. "We are going to carry out a general cleaning, without respect for gender or religion. We will shoot without question those who disregard this letter. We will finish off all tramps, marijuana smokers {and} drug users, and we are doing it for the good of everyone."

While residents in areas of the massacres are reluctant to discuss the violence, many blame at least some of the killings on policemen seeking revenge against sicarios, the young hired guns of the cartel who have killed about 350 policemen in Medellin in the past 13 months.

Gen. Miguel Gomez Padilla, commander of the police, denied the accusations, but senior civilian government officials said it was possible that some policemen were shooting first and asking questions later.

"If you killed 300 nuns the way these policemen were killed, even {nuns} would fight back," said one official. "It is a war there and has to be understood as such."

Police say the attacks, including a Feb. 16 car bomb that killed 28 people, including nine policemen, are in retaliation for the killing by police of two brothers from the Prisco family. The two ran a gang known as Los Priscos and provided personal security to Escobar for more than a decade.

Authorities said they believe that with Los Priscos now in disarray, the control Escobar and the Prisco brothers exercised over other gangs has disintegrated and the groups are vying for preeminence as well as collecting old debts.

"We will not dismantle the culture brought on by drug trafficking overnight," Mejia said. "These groups are now like puppets without a head, but they are very well financed and trying to redefine the power structure. The new types of crimes are chilling."