Anticipation built in the packed, darkened movie theater. Life and its cares began to recede. Multimedia. Then, just after midnight on Friday, fantasy became nightmare, and a place of escape became a trap, when a man strode to the front in a multiplex near Denver and opened fire. At least 12 people were killed and 58 wounded, with witnesses describing a scene of claustrophobia, panic and blood. Minutes later, the police arrested James Holmes, 24, in the theater’s parking lot.

Mayor Michael R. Bloomberg of New York, who has waged a national campaign for stricter gun laws, offered a political challenge. “Maybe it’s time that the two people who want to be president of the United States stand up and tell us what they are going to do about it,” Mr. Bloomberg said during his weekly radio program, “because this is obviously a problem across the country.” [NYTimes]