Raekwon Brown, a junior at Jeremiah E. Burke High School, was killed in a shooting outside his Dorchester school Wednesday.

Brown, 17, was the only victim. He was identified by relatives, friends and law enforcement officials. Two other male students were injured, as was a woman in her 60s, said Boston Police Commissioner William Evans.

Now, Evans is asking for witnesses to “step up” and help investigators.

"We can't let this happen in and around our schools," Boston's top cop said in a Wednesday afternoon press conference."We are appealing to the public to step up, call us and get this thing solved." 

Police responded to 56 Washington Street, just steps from the school's entrance, around 1:15 p.m.

The search for a suspect, who fled the scene, continued into Wednesday evening.

RELATED: Hearing on body cameras for Boston police canceled after Dorchester shooting

Evans said it was too early in the investigation to confirm whether a fire alarm had gone off just before the shooting, as some students told media outlets.

He also sought to assuage the fears of witnesses concerned about retaliation if they contact police, saying his department would protect the identities of tipsters.

Those with information can contact police by calling 1 (800) 494-TIPS or texting the word ‘TIP’ to CRIME (27463).

Mayor Marty Walsh, speaking to reporters, reflected on Wednesday's tragic events, and insisted that overall the "city is safe."

"Unfortunately we still have these incidences of shootings of our young people, and we have too many of them," Walsh said. "A 17-year-old kid shouldn't be dead today."

He also said counselors would be brought into schools to help students shaken up by the violence.

After the shooting, three area schools were briefly in "safe mode": the Dearborn STEM Academy, the Martin Luther King, Jr. K-8 School and the Lilla G. Frederick Pilot Middle School.