Raekwon Brown had a bad feeling on Wednesday, his friend said. When the fire alarm went off at the Jeremiah Burke High School at around 1 that afternoon, Ana Richremembered, he said “I kind of don’t want to go outside.’’

As they walked out of the school, he told her “Be safe, go home,’’ she recalled. He was always looking after his friends. A few minutes later he passed another friend, Dejah Minus. “Be safe,’’ he told her, she said. “Be safe, too,’’ she responded.

Moments later, the friendly 17-year-old who dreamed of going to college and launching a music career was bleeding on the pavement, shot to death just feet from his high school. Witnesses said dozens of students were outside when the violence exploded: Two other students were wounded and a 67-year-old woman was grazed.

On Thursday, police were still searching for the killer — and Boston Police Commissioner William B. Evans rebuked the young people who saw Brown’s slaying and have stayed silent.

“We know there are students that know exactly what happened,’’ Evans said outside the school. “Unfortunately, they are not coming forward. Everyone should be outraged by what happened, and shame on everybody if the parents and kids don’t step up here.’’

At the school, students said they spent Thursday making posters to hang at a growing sidewalk memorial for Brown, and pins bearing images of his smiling face that they would wear. Many said they hoped witnesses would speak to police.

“I wish they would come forward,’’ said Minus, the young woman Brown passed minutes before he was killed. “His mother sent him to school to come back home.’’

A distraught woman who identified herself as the 67-year-old who was grazed during the shooting described a sudden eruption of violence in front of the pizza shop and supermarket next to the high school.

“I saw when the man shot him,’’ said the woman, whose name the Globe is withholding to protect her safety. “I saw him, with a gun. And fire would come out of it.’’

The woman said she was walking to the grocery store when the shooting started, and dove for cover, but her lower leg was grazed.

“Oh God, I have nothing to do with this!’’ the woman said she yelled.

A neighbor who lives across the street and spoke on condition of anonymity to protect her safety said she ran to her window when she heard the gunfire and saw Brown in the middle of Washington Street, running toward the supermarket. At first, she said, she didn’t realize he was wounded — but then he crashed into the door of the grocery store and fell.

A man in his car began leaning on his horn to try to alert firefighters in the nearby firehouse, said the woman, and the firefighters rushed over and began performing CPR.

When she saw the young man’s stomach stop rising and falling, she said, she knew he was dead.

“I feel terrible, I still see it in my mind,’’ she said. “It hurts. How can it not hurt? I feel for the mother of this person. He’s a baby.’’

Brown’s family called for witnesses to come forward.

“Someone saw something,’’ said Venus Williams, Brown’s cousin. “We want justice for him.’’

The morning he was killed, Brown left their family home and told her, “I’ll see you when I get out of school,’’ said Williams.

“He told me he loved me,’’ she said. “It’s hard.’’

Police have received some calls from people with information, Evans said, but not enough.

“Enough with the ‘stop snitching’ stuff,’’ Evans said. “We’ve got a mother who lost her 17-year-old child. Step forward. Have some courage and solve this one.’’

Officials have said they are looking into the possibility that the shooting began as a street fight and escalated, saying there was pushing and shoving before shooting broke out.

Officials are also investigating whether the deadly encounter was gang-related, though friends, family, and City Councilor Tito Jackson have all said that Brown had no criminal record and no gang affiliation.

On Thursday, Jackson criticized Evans’s remarks about students failing to come forward with information, saying the comments “revictimized’’ young people who were already traumatized.

“I don’t know if there are young people in there that know what’s going on, but I know there are young people in there that have tears in their eyes, staff in there with tears in their eyes, people in this neighborhood who are afraid,’’ he said. “We have to deal with that first.’’

Rather than calling on students to step forward with information, Jackson called on the police to add more officers to the school force. And he called on the perpetrator to turn himself or herself in.

“You don’t belong in this community,’’ he said. “You’ve done irreparable harm to our neighborhood.’’

At a safety meeting Thursday night at the Grove Hall Community Center — near the Burke School — officials from Suffolk District Attorney Daniel F. Conley’s office assured the crowd that investigators will bring all available resources to bear to solve Brown’s murder.

Evans and Mayor Martin J. Walsh met with the family on Thursday. Evans, who is the father of a 17-year-old himself, said he was heartbroken.

“Our whole purpose was to say we’re very sorry over the loss of your young child,’’ he said. “We’ve heard more good things about him over the last 24 hours — everyone says he was a great kid.’’

Both Walsh and Superintendent Tommy Chang emphasized the importance of restoring normalcy to the Burke School, which will host its graduation as planned Friday. But signs of the previous day’s violence marked the neighborhood.

Police officers stood guard in front of the school’s red-brick building. Near the shooting scene, the sidewalk memorial grew, with flowers, stuffed animals, and balloons that read, “We’ll Miss You.’’ Students said they were afraid to walk outside of the school.

“The time it happened at is the time we have lunch,’’ said Nicholas Hollins, an 18-year-old senior, who often goes to the pizza shop near where Brown was killed. “For it to happen around that time, it could have been anybody.’’

As they organized a vigil in his memory, Brown’s family struggled to accept that it had been their “Ray Ray.’’

“At the end of the day, we have to come to terms with this and accept that we have to lay our young brother to rest at the age of 17,’’ said his brother, Stanley Wiggins, 28. “So that means no graduation, no prom, no him having no family or nothing like that; that’s the crushing part for us.’’

One of the people shot Wednesday was Brown’s cousin. He limped as he walked on Thursday night.

“I don’t think I’m feeling OK,’’ he said.

At the vigil, more than 100 mourners gathered, placing balloons and lit candles at the memorial, and the Rev. William Dickerson delivered an impassioned prayer.

“We pray, heavenly father, that this young warrior will not be forgotten,’’ Dickerson intoned. “We pray that justice will come forth . . . in the midst of this painful reality.’’

He prayed that the community would “refute the violence, refute the bloodshed.’’

Through his grief and disbelief, Wiggins had a message for whoever killed his brother: “I forgive you. We want them to do the right thing by coming forth and just turn yourself in because he didn’t deserve this.’’

Jeremy Fox, Travis Andersen, and Nicole Hernandez of the Globe staff, and Globe correspondent Miguel Otárola contributed to this report. Evan Allen can be reached at evan.allen@globe.com.