Get tough with downtown violent offenders — and work on preventing youth violence.

Another vicious and random assault has put downtown Minneapolis on high safety alert. This time, a man leaving last week's St. Patrick's Day parade with his family was sucker-punched in the face and knocked into a wall when a swarm of young people surrounded his group. The 56-year-old victim is the brother-in-law of a Downtown Council board member who witnessed the attack.

As Star Tribune columnist Jon Tevlin reported this week, the victim's teenage son broke through the crowd and quickly brought police officers to the scene. But even more young people were drawn to the melee, forcing officers on bicycles to surround the family and escort them inside a building for safety.

One of the most disturbing aspects of the incident was that so much advance work was done to prevent violence this year. During 2015 St. Patrick's Day activities, similar "flash mob'' problems occurred as roving bands of young people disrupted the celebration. This year, police say social media posts called for large groups to gather downtown, which prompted an increased presence of police and youth workers. Clearly, the heightened law-enforcement presence didn't seem to be much of a deterrent.

This type of random crime can understandably cause customers to stay away from downtown businesses as well as discourage downtown living. To maintain an active, vibrant downtown, the city and community must double down on prosecuting offenders and bolster youth violence prevention.

For the past several years, a coalition of stakeholders — including the city, Hennepin County, the Sheriff's Office, schools, Metro Transit and downtown businesses — has worked on downtown youth violence prevention. The strategy includes summer job opportunities and other constructive activities, as well as more youth workers to help guide teens onto positive paths. The group also has worked on expanded camera surveillance to support enforcement and faster identification of offenders.

In the wake of this year's attack, Downtown Council President and CEO Steve Cramer said the council is offering a $5,000 reward for information leading to the arrest of the assailant because, he said, "someone knows who engaged in this unlawful conduct. … As a community, we must agree to define such behavior as outside the bounds of what we will accept. We simply won't tolerate it, nor will we cede our streets to such brazen acts."

We couldn't agree more. The Star Tribune Editorial Board — itself a part of a downtown Minneapolis business — stands behind expanded efforts to catch and punish offenders, patrol the streets and prevent youth violence.