VATICAN CITY--Pope John Paul II rose from his hospital bed and celebrated Mass yesterday for the first time since he was wounded in an assassination attempt Wednesday. Doctors said that barring setbacks he will fully recover.

Dr. Emilio Tresant chief of the medical staff at the pope's hospital said the pope will soon be moved out of the intensive care ward--perhaps on his 61st birthday today--and should be able to leave the hospital "in about a month."

The pope sat in a chair for about a half hour a medical bulletin said, after saying in a tape-recorded Mass that he forgives "that brother of ours who shot me."

The papal message, in a soft but unfaltering voice was played to a throng in St. Peter's Square. It brought relief and tears to listeners, who were hearing the pope for the first time since he was wounded Wednesday.

Polish Catholics also wept at the sound of the pope's voice yesterday, and in Krakow, where he was once archbishop 300,000 faithful prayed for his recovery from gunshot wounds.

Poles also prayed yesterday for the dying primate of their Roman Catholic Church, Cardinal Stefan Wyszynski, who once was the pope's mentor and who for 33 years was the embattled church's leader.

The huge iron gates of Wyszynski's Warsaw residence were adorned with purple and red tulips, and inside, the bedridden 79-year-old cardinal--who was given last rites Saturday--was in serious condition with what church officials have described only as a "gastric illness."

Meanwhile, Rome's police headquarters said two--not three--bullets are believed to have been fired by the accused Turkish gunman, wounding the pope and two American pilgrims who were in St. Peter's Square. No major leads were reported in the investigation of whether the shooting was a conspiracy. Some newspapers, quoting unnamed sources, hinted at a second gunman, but police publicly denied this.

"With deep emotion, I thank you for prayers and I bless you all," the pope said in a message which was recorded at Rome's Gemelli Policlinico Hospital and played over a loudspeaker a short time later for the crowd in St. Peter's Square.

"I am particularly close to the two persons wounded together with me," he said." I pray for that brother of ours who shot me and whom I have sincerely pardoned."

As his soft, slightly slurred but steady voice boomed over the square, a crowd of 15,000 broke into cheers. Some wept. Many knelt and prayed.

"United with Christ, priest and victim. I offer my sufferings for the church and the world," he said. The words, in Italian, were carried on Vatican Radio and were broadcast in his native Poland.

The man charged with shooting the pope. Mehmet Ali Agca, 23, remained under heavy guard in Rome police headquarters.

According to newspaper accounts, one 9mm bullet struck the pope in the right arm, exited and then wounded Ann Odred. 58, of Buffalo, N.Y., in the chest. The other bullet was said to have nicked the pope's left hand, passed through his abdomen, then hit the other American, Rose Hall, 21, in the elbow.

The women were recovering yesterday in Rome's Santo Spirito Hospital.

John Paul II passed a restful night and was taken off painkillers, his physicians said. His intestines, damaged in at least 12 places, were reported showing signs of returning to normal.

Doctors said the pope's intestinal bypass may be closed within a week, but added that surgery on the two bones of his left index finger--fractured in the shooting--was not yet being considered.