Chicago's first 80-degree day in seven months yesterday brought a wave of violence, with an average of one shooting per hour at one point. There were 20 shootings total; three were fatal.

The violence came less than a month after the police department announced that crime in the city had fallen 8 percent in the year’s first quarter, compared with the same period a year earlier, and 15 percent from 2011.

Murders fell by 42 percent in the quarter and shootings by 27 percent, the department said in a news release.