CHICAGO (CBS) — A 15-year-old boy was killed and at least 26 other people have been wounded in Chicago shootings throughout the Memorial Day weekend, including two people wounded in a shooting on I-57 on the Far South Side.

The 15-year-old boy was killed about 6:30 p.m. Sunday in a Lawndale neighborhood drive-by shooting that also left a 16-year-old girl wounded on the Southwest Side. The two teenagers were in a gangway in the 1600 block of South St. Louis when someone fired shots at them from a passing gray vehicle, according to Chicago Police. The boy was shot in the back and taken to Mount Sinai Hospital, where he died. The Cook County medical examiner’s office has not provided information on the fatality. The girl suffered a graze wound to the back and was taken to Mount Sinai Hospital.

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With a single fatal shooting since Friday evening, this year’s holiday weekend has been much less violent than last year’s.

In 2016, 47 people were shot, four of them fatally, by midnight Sunday of the long holiday weekend, which is widely viewed as the unofficial start of the summer — with an accompanying surge in city gun violence. By the end of that weekend, 69 people had been shot, leaving 6 dead. Twelve people were killed and 43 wounded over 2015’s holiday.

To combat this year’s anticipated carnage, Chicago Police are flooding the streets with 1,300 extra patrol officers through early Tuesday.

That happens to be about the same number of people who have been shot in the city so far this year: 1,315, according to Chicago Sun-Times data. Of those, 223 have died.

About 2:45 a.m. Monday, someone inside a black Dodge Charger fired shots at a gray Acura while the vehicles were traveling in the northbound lanes of I-57 near 115th Street, according to Illinois State Police. The Acura was then rear-ended by a third vehicle. One person inside the Acura was shot in the buttocks, while another person suffered a gunshot wound to the lower back.

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Two men were taken from the scene in serious-to-critical condition to Christ Medical Center in Oak Lawn, said Chicago Fire Department spokesman Jeff Lyle. Two other people were taken in good condition to Roseland Community Hospital. Additional details on the shooting were not immediately available.

Earlier Monday, two men were wounded in a drive-by shooting outside a BP gas station in the Archer Heights neighborhood on the Southwest Side. The men, ages 21 and 22, were driving south at 1:24 a.m. in the 4500 block of South Pulaski when someone in a dark-colored SUV fired shots in their direction, police said. The younger man was shot in the right knee, while the older man suffered a gunshot wound to the right leg. They were both taken to Christ Medical Center in Oak Lawn, where their conditions were stabilized.

“This is sad, man,” said the 37-year-old cashier at the gas station, who asked to remain anonymous. “I’m sick of seeing this s–t. I wish it would just end already, this violence is not necessary.”

At least 21 other people have been shot in Chicago since 7 p.m. Friday.

On Friday night, 53 people were arrested, including 30 who were arrested during pre-emptive raids, in anti-violence initiatives targeting the South and West sides, according to a statement from Chicago Police spokesman Anthony Guglielmi. Police teams also recovered four illegal guns and issued more than 70 traffic citations.

Seventy-seven people were arrested Saturday night into Sunday morning, Guglielmi said. Ten illegal guns were seized and 176 traffic citations were issued.

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(Source: Sun-Times Media Wire © Chicago Sun-Times 2016. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)