BOGOTA, COLOMBIA, SEPT. 26 -- Gunmen suspected of belonging to the Medellin cocaine cartel murdered 19 people in Cali in what police and narcotics experts said today could be a bloody renewal of the feud between two rival groups of drug traffickers.

The cartels based in Medellin and Cali have long fought over tactics and foreign cocaine markets, and the disagreements have turned violent on several occassions.

According to a police bulletin, at around 7:30 p.m. Tuesday about 20 men dressed as anti-narcotics troops and using three vehicles rode into the luxurious Villa La Legua farm 20 miles east of Cali, where a soccer match was in progress and an elaborate dinner was being prepared.

The gunmen, using automatic weapons, killed two people at the entrance to the property, 10 in the main house, including the female cook, and four men on the soccer field. Three others died later in a hospital.

Cali, 200 miles southwest of the capital, is Colombia's third-largest city; Medellin, 175 miles northeast of Bogota, is the second-largest.

"It is difficult to establish the exact motive at this time, but every indication is that it is a vendetta against Cali or a group in Cali," said Col. Rodrigo Millan Bautista, commander of the Cali Municipal Police. "From the information we have, the perpetrators came from the province of Antioquia," of which Medellin is the capital.

Asked if he meant a renewal of the war between the two cartels, he said, "That is what I was referring to."

Among the indications that the killing was not a simple criminal attack, narcotics experts said, was the fact that the people who fled the killers left behind 23 luxury vehicles that no one has claimed. Police have been unable to identify the owner of the property, which includes a well-lit soccer field and luxury accomodations.

Fighting between the two groups is not new. In 1988 the cartels engaged in a bloody war when Medellin cartel leader Pablo Escobar tried to move cocaine into the New York market, traditionally a Cali stronghold. In May the two groups also carried out a series of car bombing against each other, killing six people, wounding dozens and causing hundreds of thousands of dollars in damage.

The Medellin cartel has publicly said the Cali group is working for the police to help destroy the Medellin organization in an effort to eliminate Escobar and grab a larger share of the foreign market, especially in Europe. Narcotics experts said this could be a motive for the new violence.

While the Medellin group has violently attacked the government and suffered the brunt of the 13-month police crackdown, the Cali cartel has conducted its business quietly, drawing little government heat.

The massacre seemed to signal an end to the relative peace Colombia had experienced following the July 27 declaration of a unilateral truce by leaders of the Medellin cartel, who call themselves "the Extraditables."

Last week, the Extraditables broke that truce and took responsibility for kidnapping Francisco Santos, managing editor of El Tiempo, the nation's largest newspaper; Marina Montoya, sister of the ambassador to Canada; and Diana Turbay de Uribe, editor of Hoy por Hoy magazine and daughter of former president Julio Cesar Turbay.

The Extraditables, claiming to be a "political-military organization," are demanding negotiations with the government. President Cesar Gaviria said he will not negotiate with the traffickers.