September 6, 1986

At least 15 people were killed and scores wounded Friday night when the Arabic-speaking hijackers of a New York-bound Pan American jumbo jet suddenly began shooting and detonating grenades inside the darkened passenger cabin. Hundreds of panic-stricken travelers, many of them splattered with blood, escaped out the doors of the parked Boeing 747. At the same time, Pakistani commandos outside the plane apparently also fired shots, killing two of the gunmen, according to the Pakistani authorities. At least two other hijackers were reported taken into custody. ''They herded everybody toward the center and then started firing indiscriminately,'' K. F. Bhatoa, manager of the Trade Fair Authority of India, said of the gunmen. He had boarded in Bombay, India, and was flying to Frankfurt.

President Reagan today condemned the seizure of a Pan American jet as a ''cruel and sinister terrorist act,'' and he accused the hijackers of ''a despicable and cowardly crime.'' ''Nothing can justify such barbarism,'' Mr. Reagan said. ''We can think of no punishment too severe for the criminals responsible. We are confident that those who perpetrated this brutal act will be brought to justice.''

Governor Cuomo and the Vicar General of the Archdiocese of New York traded strong words yesterday over the responsibility of a Roman Catholic to adhere to church teaching, particularly on the question of abortion. The Vicar General, Bishop Joseph T. O'Keefe, declared that Mr. Cuomo was ''so smart he would confuse young people,'' and said ''under no circumstances would I invite him to speak to young people at a graduation.'' ''I've known the Bishop for a long time,'' Mr. Cuomo responded. ''I respect him now, and I always will. Regrettably, I do not agree with him.''

An unmanned Delta rocket carrying a secret payload for an antimissile system was fired into space today, marking a major United States success in a year plagued by catastrophe and mishap. The secret project was the first major experiment in President Reagan's antimissile plan to be conducted entirely in space. The experiment, involving one satellite tracking and destroying another, was declared a complete success by the Pentagon. At 11:08 A.M., amid unusual secrecy and security, the $42 million rocket rose from pad 17B of the Cape Canaveral Air Force Station, arcing due east into a partly cloudy sky.

John A. Walker Jr. failed recent polygraph tests and prosecutors are concerned that the Navy veteran is lying about the origins of his career as a Soviet spy, law-enforcement officials and others familiar with the case said today. One source close to the investigation said that Mr. Walker, a former Navy warrant officer, had been found to be deceptive when questioned about whether he or his brother Arthur had formed a spy ring that the Government has described as one of the most damaging espionage operations in American history. If Arthur J. Walker was the one who started the espionage ring, officials said, it could mean that the spy operation did even more damage than is now believed. In his Navy career, Arthur Walker, who was a lieutenant commander when he retired, had access to extensive secret information about the United States submarine fleet.