By Tod Robberson
Washington Post Foreign Service
Thursday, March 24, 1994; Page A01

MEXICO CITY, MARCH 23 -- Luis Donaldo Colosio, the ruling party's presidential candidate and hand-picked successor to President Carlos Salinas de Gortari, was shot and killed today while campaigning in the northern border city of Tijuana.

Witnesses said Colosio, 44, candidate of the ruling Institutional Revolutionary Party (PRI), was shot at least twice, in the head and abdomen. He was immediately rushed into surgery at Tijuana General Hospital. Colosio died at 8:10 p.m. (11:10 p.m. EST), about three hours after he was shot, according to his campaign press secretary, Leavano Saenz.

At least two gunmen were seen firing pistols at point-blank range as Colosio was mingling with a crowd of 3,000 to 4,000 supporters during a campaign stop in the impoverished neighborhood of Lomas Taurinas.

Television footage showed confusion in the crowd as police hovered over Colosio and wrestled with the gunmen, one of whom was seen waving a pistol after opening fire. Colosio was lifted by the arms by several men. He was bleeding profusely from wounds to the head and chest.

Authorities said one of the assailants has been tentatively identified as Mario Arburto Martinez. He was shown on Mexican television holding a pistol to Colosio's chest as the candidate was being rushed into an ambulance. The Mexican attorney general's office described Martinez as a 23-year-old industrial mechanic who lived in Tijuana, Reuter reported. Officials said he was a native of the western state of Michoacan and used a .38-caliber handgun in the killing.

Police also arrested Vicente Mayoral Valenzuela, believed to be about 40, as an accomplice. He has been identified as a former member of the Federal Judicial Police.

Mexican radio stations referred to today's shooting as an "apparent assassination attempt," although the gunmen's motives were unknown. It was the first time in more than 60 years that a PRI presidential candidate has come under such an attack, said Tulane University Mexico specialist Roderic A. Camp.

"This will have incredible consequences for Mexico," Camp said. "The country has no mechanism for dealing with something like this, which will tend to magnify the importance and impact of what has happened."

Salinas made a brief statement to the nation tonight saying he was sending Mexican Attorney General Diego Valades to Tijuana to head the investigation into the killing.

Colosio's shooting could radically change the political landscape in Mexico at a crucial moment in campaigning ahead of the Aug. 21 presidential elections, Camp said. It also could have an important impact on negotiations to resolve an 11-week-old peasant uprising in southern Mexico.

On Nov. 28, Salinas designated Colosio as the PRI presidential candidate, effectively selecting him as the next Mexican president when Salinas's six-year term expires in December. The PRI has held uninterrupted control of the presidency for the past 65 years, and under Mexican law Salinas cannot seek reelection.

In Tijuana tonight, hundreds of people sat on the steps of the hospital where Colosio died, holding lighted candles in a vigil, staff writer Christine Spolar reported. "Everyone saw it {the shooting} on television," said Calandario Runa, a roofer and PRI supporter who had spent most of the evening at the hospital.

"People are very upset," he said. "They thought he was going to be good for Mexico but he never had a chance."

Before becoming the PRI candidate last November, Colosio served in Salinas's cabinet as secretary of social development, and he was no stranger to mingling in large crowds. His previous job required him to travel extensively throughout the country and meet on an almost daily basis with peasant farmers and impoverished Mexicans in need of government assistance.

He won Salinas's confidence -- and garnered national popularity -- by successfully directing the president's national social welfare program, Solidarity. Before joining the cabinet, Colosio served as president of the PRI and helped direct Salinas's 1988 presidential campaign.

Colosio's candidacy has been immersed in controversy from the outset. His main rival for the PRI candidacy, former Mexico City mayor Manuel Camacho Solis, resigned from Salinas's government to protest being passed over in favor of Colosio. Camacho subsequently eclipsed Colosio's campaign when he was named the government's representative in peace negotiations with peasant rebels in the southern state of Chiapas.

Camacho used the position to test the political waters for a potential independent presidential campaign or possibly to replace Colosio on the PRI ballot.

Camacho's actions threatened to split the PRI, undermine Colosio's campaign and potentially lead to the first loss by a PRI presidential candidate since 1929.

The confrontation between the two ended only on Tuesday, when Camacho, under intense pressure from Salinas and the PRI, announced he was withdrawing his name from consideration as a candidate. Colosio welcomed the announcement and offered full support for Camacho in his efforts to reach a peace accord in Chiapas with rebels of the Zapatista National Liberation Army.

In Chiapas tonight, Camacho said he was shocked by the shooting and said it could have a serious impact on the peace process.

With the death of Colosio, Camacho might become Salinas's choice to carry on the PRI campaign.

Camp said the shooting could have the immediate effect of tainting Camacho because of the intense rivalry that existed between the two until Tuesday. "There might be some people who will associate Camacho with this attempt, whether it is deserved or not," he said.

Tijuana has been the center of drug-related violence and gangland-style shootouts in recent months, including an inner-city gun battle earlier this month involving federal agents, members of the nation's most notorious trafficking organization and Baja California state police who allegedly were serving as bodyguards for drug lords. Tijuana-based drug lords were implicated in the killing last May of Roman Catholic Cardinal Juan Jesus Posadas Ocampo in the central city of Guadalajara.