MARACAIBO, VENEZUELA, JUNE 17 -- Venezuelan military helicopters today ferried into this provincial capital the casualties of a cross-border attack by Colombian gunmen as the government released new details about the shootout -- including the fact that it occurred six days ago.

Mothers cried and reporters surged onto the tarmac as a National Guard helicopter carrying wounded soldiers landed at the military airstrip here, reminding the nation that Venezuela has become embroiled in a violent war against drugs.

Maracaibo serves as the headquarters for the guard's antidrug efforts in the nearby Sierra de Perija mountains, the scene of a shootout last Friday that left at least nine guardsmen dead and 10 wounded.

Numerous conflicting reports have emerged about the incident, including the total number of casualties. Yesterday, military authorities said 15 National Guardsmen had been killed.

The government, which did not announce the bloody battle until yesterday, is blaming Marxist guerrillas of the Colombia National Liberation Army, or ELN by its Spanish initials, but officials have not provided public proof of the claim.

Military sources said the Venezuelan soldiers were attacked by troops fighting for Latin America's drug lords, however.

"We are on full alert," said Gen. Marcial Rojas Aguero, who heads the National Guard's efforts to plug Venezuela's porous borders against drug traffickers.

Venezuela is now coordinating with Colombian officials an offensive aimed at surrounding the attackers and preventing their escape, he said.

{President Jaime Lusinchi on Wednesday urged the Colombian government to match Venezuela's efforts against guerrillas, drug producers and drug smugglers, The Associated Press reported.}

The Venezuelan government says Colombians have been crossing the border into the sparsely populated Sierra de Perija to cultivate marijuana plants and coca bushes. The leaves are then moved back into Colombia for processing and shipment to the United States and Europe.

For the past two years, the National Guard has attempted to block shipment and production of drugs in Venezuelan territory by conducting search-and-destroy missions in the Sierra de Perija. The guards attacked on Friday were members of an antidrug unit.

Authorities assert that the assault, in which the guerrillas reportedly used grenades, antitank rockets and mortars, was an act of revenge for the guard's destruction of a 320-acre marijuana and coca farm discovered last month not far from the scene of Friday's shoot-out.

According to military sources, the 23-member National Guard patrol was sleeping when gunmen attacked. Four guardsmen who escaped uninjured trekked for more than two days to get to the nearest guard post, and it was not until they arrived that the government learned of the attack.

Rojas Aguero said at least 60 attackers, or "narco-guerrillas," were involved in the assault and some of them were killed, but he could not say how many. "There was a lot of confusion there. It was a massive attack," he said.

The pro-Cuban ELN, one of Colombia's three main guerrilla groups, has been building a base of operations in Colombia's oil-producing areas, not far from the Sierra de Perija.