Criminal cases are being pursued against a handful of people stemming from the mayhem that erupted on the night of St. Patrick's Day along Nicollet Mall in downtown Minneapolis, the Hennepin County attorney's office has announced.

Several hundred young people, most of them teens, headed into downtown that day on free bus and light-rail rides, ran in the streets, blocked traffic and got into fights, police said. Metro Transit, Park and Minneapolis police made several arrests and pushed teens onto buses and trains heading out of downtown. Two of the disorderly young people were treated for minor injuries, police said.

Elijah Morgan-Hamilton, 21, of New Hope, was charged with felony second-degree riot. A man was arrested with Morgan-Hamilton on suspicion of possessing cocaine; charges in that case are awaiting test results on the substance.

A 16-year-old girl was arrested on suspicion of riot and a 15-year-old boy on assault allegations. Their cases are in the juvenile court system, legally preventing the county attorney's office from saying anything further.

"At the moment, these are all the cases we have," County Attorney Mike Freeman said Monday. "We have dealt with them as firmly as the law allows, and if police are able to bring us more cases after further investigation, we will certainly look at charging them, as well."

Within a day of the incident, Mayor Betsy Hodges and other city leaders spoke up to assure the public that downtown is a safe place to visit.

"We want our young people to enjoy all of the great events that downtown has to offer," Freeman said, "but they have to behave appropriately or they will pay the price."

The unrest erupted about 7:40 p.m., when police saw a large number of young people at 6th Street and Nicollet Mall, according to the criminal complaint against Morgan-Hamilton. Fights would break out and the crowd would run toward them, the complaint continued.

In this instance, Morgan-Hamilton and another person were running, and Morgan-Hamilton had in his hand a knife with an 8-inch blade. He dropped the weapon after spotting police, according to the complaint.

Morgan-Hamilton told police that a friend had given him the knife and that he "brandished it at others in the crowd in self-defense," the complaint read.

Along with the case against Morgan-Hamilton, the cocaine investigation and the two juvenile prosecutions, allegations against another adult that were brought to the county attorney's office are being deferred to the city attorney for possible charging as a gross misdemeanor or misdemeanor. Authorities have said nothing more about that case.