CHICAGO -- Chicago began the unofficial start of summer over Memorial Day weekend with dozens of shootings that killed six people and wounded 56 others, contributing to a spike in violent crime in the city this year.

There were 48 shooting incidents in the city from 5 p.m. Friday through midnight on Monday, the police department said Tuesday. That's the same number of shootings and wounded people as last year's Memorial Day weekend, but fewer than half of that weekend's 14 fatal shootings.

The police were bracing for the holiday weekend, with Superintendent Eddie Johnson, in his first major test since being sworn in last month to head the beleaguered department, putting more officers on the street in the hopes of stemming some of the violence.

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There was a strong police presence in some of the most violent neighborhoods on the city's West Side and South Side. But there were still dozens of people who were shot in the most heavily patrolled areas of the city.

The state police, too, were out in force, deploying more troopers to area expressways due to a spike in fatal shootings on such thoroughfares this year. A state police spokesman said the weekend ended without any shootings on area expressways.

The roads didn't escape the violence, though. A 15-year-old girl who was a passenger in a vehicle on scenic Lake Shore Drive on the city's North Side was fatally shot early Saturday. And a woman was struck and killed by a car on that roadway early Sunday while trying to escape muggers, police said. Her death wasn't among the six homicides, but it could later be classified as such if the suspects are caught and charged with murder, they said.

The holiday weekend was of particular concern because it is the unofficial start of the summer, when there are typically more shootings in Chicago, and because there has been a marked increase in homicides this year, with 242 through the end of Monday as compared to 160 during the same period of last year. Shooting incidents are also up this year, with 1,233 compared to 812 during the same period of 2015.

After a particularly violent first three months of the year, when homicides and shootings were up by at least 70 percent, the violence has slowed somewhat. But the city is still on a pace to end the year with more than 500 homicides for the first time since 2012, when the soaring number of gun deaths captured widespread attention.