Police said Monday they were questioning two men in connection with a suicide attack at a Shiite mosque in eastern Pakistan that killed three people plus the bomber — the latest violence in what appears to be rising strife between Shiite and Sunni Muslims. Two security guards died in the attack Sunday while confronting the bomber and preventing far more deaths by blocking his entrance into Husainia Hall mosque in Lahore during evening prayers. The bomber and a passerby also were killed and eight were wounded, Punjab province Law Minister Raja Basharat Illahi said. Seventy to 80 people were in the mosque for prayers when a man carrying a briefcase tried to enter but was blocked by the guards, officials said. A bomb in the briefcase exploded after a scuffle, during which one of the guards opened fire. Two men were picked up in the neighborhood where the mosque is located shortly after the bombing, a senior police official in Lahore said on condition of anonymity. The men — who have not been formally arrested — looked suspicious and tried to run away when police confronted them, he said. Their identities were not given.The bombing in Lahore came the same day that thousands of people mourned two Sunni Muslim clerics who were gunned down in the southern city of Karachi a day earlier. The bomb attack was the third this month against a religious target in Punjab in apparent sectarian violence between Shiite and Sunni Muslims.