President Patricio Aylwin met in the early morning hours Tuesday with his National Security Council to discuss anti-terrorism measures following the assassination of a senator allied with former President Augusto Pinochet.

Sen. Jaime Guzman, 45, was shot to death Monday afternoon by four people in a car while his own vehicle was stopped at a traffic light as he left Catholic University in Santiago, where he was a law professor. His killers fled in a stolen taxi, which was abandoned several blocks away, police said.Guzman was wounded in the chest and stomach and died during surgery at Military Hospital, the government said.

Guzman, the main author of the 1980 constitution that was the basis for the transition of the 161/2-year Pinochet dictatorship to democracy, had bitter enemies in left-wing parties, but he refused to have bodyguards.

Police have not yet attributed the killing to any specific group, nor was there any immediate claim of responsibility for the attack, the third this year to target a prominent rightist figure.

Angered by the assassination, rightist protesters gathered outside the hospital, chanting anti-government slogans and voicing support for Pinochet. Many called for a military coup.

Authorities suspect left-wing terrorists for assaults last year in which retired national police Gen. Luis Fontaine was killed on May 10 and retired air force commander Gen. Gustavo Leigh Guzman was seriously wounded by gunmen on March 21.

On Nov. 17 of that year Canadian shrimp exporter James Thomas died when a bomb placed by terrorists at a baseball game between the University of Chile and the U.S. Chamber of Commerce.

Aylwin, inaugurated on March 11 of last year, is Chile's first elected, civilian president to hold office since President Salvador Allende was ousted in a coup d'etat on Sept. 11, 1973, which brought Pinochet to power.

Aylwin's year-old government has been plagued by charges it is weak on terrorism and combating crime.

"It is time for the government to get tough," said Andres Allamand, president of the right-wing National Renewal Party.