Short answers, pulled from the story.
Alexander II was killed by two members of the revolutionary organization Narodnaya Volya. Nikolai Rysakov threw the first bomb, which damaged the Tsar's carriage but left him unhurt. Ignacy Hryniewiecki threw the second bomb at the Tsar's feet, fatally wounding both Alexander II and himself.
Alexander II was assassinated on the 13th of March 1881 on the embankment of the Catherine Canal in Saint Petersburg, Russia. He died later that afternoon in his study at the Winter Palace at 3:30 PM.
Sophia Perovskaya took command of the operation after the plot's chief organizer, Andrei Zhelyabov, was arrested two days before the attack. On the day of the assassination, she signaled the bomb-throwers by blowing her nose with a handkerchief when the Tsar's carriage changed its route, redirecting the assassins to the Catherine Canal. She was arrested on the 22nd of March 1881 and executed on the 15th of April 1881.
The Church of the Savior on Blood in Saint Petersburg was built on the exact site where Alexander II was fatally wounded. Construction began in 1883 under Alexander III and was completed in 1907 under Nicholas II. Inside, a shrine decorated with topaz and lazurite marks the precise spot, with the original cobblestones of the old road exposed in the floor beneath it.
The assassination triggered a wave of antisemitism and violent pogroms across the Russian Empire. Pogroms struck 166 towns in the south-western provinces, destroying thousands of Jewish homes and killing and injuring large numbers of people. The government also passed the May Laws, and Alexander III reversed the relatively tolerant policies toward Jews that his father had put in place.
Six conspirators, including Zhelyabov, Perovskaya, Kibalchich, Rysakov, Mikhailov, and Helfman, were tried and sentenced to death. Five were hanged on the 15th of April 1881; Helfman's sentence was deferred due to pregnancy and later commuted by Alexander III. She died of a post-natal complication in January 1882. Yemelyanov was sentenced to life at hard labor and pardoned after 20 years. Vera Figner was captured in 1883 and eventually freed after 20 years following a plea from her dying mother to Nicholas II.