04/09/2012 11:06 am ET

Adrian Luna, 13, Dead: Teen's Slaying One Of More Than 20 Weekend Shootings In Chicago

Police say a shooting that killed a 13-year-old boy in Chicago's Brighton Park neighborhood this weekend, one of four fatalities among 21 wounded by gunfire since Friday, is evidence that the city's problem with gun violence could be escalating.

Witnesses say shooters yelled gang slogans before opening fire on Adrian Luna, 13, and two other males ages 15 and 16 in front of Luna's home on S. Spaulding Ave. just before 10 p.m. Saturday, NBC reports. Relatives say the 7th grader at Hernandez Middle School was not involved in a gang, but his neighborhood is one of many that has seen an uptick in violence this year.

"He was just a baby," Erik Lopez, 28, another of Adrian’s brothers, told the Chicago Tribune. "They took a kid full of life, a kid full of joy."

Luna was pronounced dead at 11:19 p.m. Saturday at Mount Sinai Hospital, and the 15-year-old shot at the scene is listed in critical condition at John H. Stroger Jr. Hospital, Fox Chicago reports. The 16-year-old, who was shot in the forearm, was listed in fair condition at Stroger Saturday.

Police say two shooters wearing masks approached the teens from a gangway and jumped into a van waiting on 47th and Christiana after firing, according to WGN. Crime Stoppers is offering a $1,000 reward for any information about the shooting.

A motive for the shooting has not yet been identified, but Central Area detectives are investigating.

The city has seen a slew of shootings every weekend since early March. In mid-March, the city reached 100 homicides for the year -- the earliest in the last seven years.