CHICAGO (CBS) — Police are asking the community for help in tracking down the killer of a 13-year-old Chicago boy.

Roberto Luna was murdered over the weekend while sitting on his steps. Police say he and his friends had no gang ties, but that didn’t stop them from being shot.

CBS 2’s Mike Puccinelli has the story of one of the boys who survived.

With his shirt still spattered with blood and his arm in a cast, 16-year-old Cerafin Gonzalez walks home from the store with votive candles. They were bought for Roberto’s memorial.

“He was like a brother. He was a really good friend,” Gonzalez says.

Now, his friend is gone — shot dead Saturday night as he sat on the steps in front of his house. Gonzalez was there, too, when two attackers walked up and opened fire.

“They just came and shot us without any warning,” he says.

Luna was hit as many as 11 times and died in his brother’s arms. A 15-year-old was hit several times and was in surgery Monday at Stroger Hospital.

The killers surprised the teens by walking out of a gangway. They asked the teens if they were in a gang. The teens said no but the strangers opened fire, anyway, at point blank range.

“I just guess God gave me the strength to run, because first I pretended they shot me in the heart and I fell down to the floor and I thought if they stopped shooting me, I had a chance to run and I ran,” the teen says.

Ana Gonzalez is Cerafin’s older sister.  She says her brother will never be the same in light of what he saw.

“He doesn’t stop thinking about it. He doesn’t stop crying. He hasn’t even changed from his clothes because he doesn’t want to forget,” she says.

And neither does Roberto’s brother.

“He’s the one that made everybody laugh, everybody,” Mario Lopez says.

There was no laughter Monday, just tears for a 13-year-old boy, a young son, brother and friend.

So far, police have no suspects and no solid leads. They hope that someone in the neighborhood will come forward with information that will help them catch a killer.

Meanwhile, counselors were on hand Monday at Roberto’s school to speak with his seventh-grade classmates about the sudden and violent loss of their friend.