Updated 12/15/14 – 3:24 p.m.

CHICAGO (CBS) — Three more suspects have been charged Monday afternoon in the murder of a 15-year-old boy who was killed while protecting his brother from muggers this weekend. One suspect had been charged on Sunday.

Demario Bailey was walking to basketball practice with his brother, Demacio, on Saturday, when four men approached them in a long, dark viaduct on 63rd Street, just west of State Street, and announced a robbery.

A fight ensued when the robbers started going through the boys’ pockets, and when Demario tried to defend his brother, one of the robbers shot him in the chest. He died within minutes.

One person – 17-year-old Carlos Johnson, was charged on Sunday with first-degree murder, armed robbery, and attempted armed robbery in connection with Demario’s death. He was ordered held without bail Monday afternoon.

On Monday, Deafro Brakes, 17, Tarik Brakes, 16 and Isiah Penn, 17 were each charged with two counts of murder and two counts of attempted armed robbery with a fire arm, according to the Cook County State’s Attorney’s office.

At Johnson’s bond hearing, prosecutors said he was not the one who shot Demario, but was part of the group of muggers. The same group robbed two other people shortly before attacking Demario and Demacio.

Meantime, students and staff at Johnson College Prep, where Demario was a sophomore, were mourning the loss of a beloved teen.

Johnson principal Garland Thomas-McDavid said more must be done about gun violence in the Englewood community.

“It’s one thing to be reactive. We need a proactive force out here, so that these children are not being put in harm’s way,” she said.

Grief counselors were talking to students and staff at Johnson on Monday, to help them cope with Demario’s death.

“I’ll just remember how he made people laugh,” freshman Keyara Green said.

Sophomore Centrell McNelly said he last saw Demario at school Friday.

“We didn’t even say bye. It’s just difficult. I still can’t believe he’s gone. It just feels like a dream,” McNelly said.

Relatives said the muggers who killed Demario wanted his new Columbia winter jacket, and hassled Demacio. Demario refused to give up his coat, and tried to protect his brother, and was shot protecting both.

The twins were just three days shy of their 16th birthday when Demario was slain.

“Even though he’s gone, I’m going to still feel his presence inside the school; go up to his locker and just think about him,” sophomore Kayla Foster said.

One mother said she nearly lost her son in August.

“He was shot in the leg, and it broke the femur,” Mary Ann Moore said. “I was at church on that Sunday, so my sister got the call, and we had to come home. He was walking from his grandma’s house, which is right around the corner from me, and a car came out of alley and just started shooting,” Mary Ann Moore said.

The school was planning a memorial assembly for Tuesday, which would have been Demario’s 16th birthday.