The police investigation of 3-year-old Terrell Mayes' death began with a call so routine it happens every day in Minneapolis: a "shots fired" report.

That's how police refer to a report of gunfire, and 278 times this year police have responded to such a call and found shell casings, a bullet hole, a witness or other evidence of a gunshot, according to city records requested by the Star Tribune Wednesday. The city's most recent map of reported gunshots, published on the city website, shows five people had been injured by gunfire in the week before Terrell Mayes was shot Monday night.

If Terrell had gotten a single step closer to the upstairs closet where his family frequently fled to avoid the gunshots that punctuated the air around their home in north Minneapolis, officers would have filed just another confirmed gunshot report.

Instead, for the second time in a decade, a stray bullet burst through a house and killed a Minneapolis child.

Authorities said they believe the bullet that killed Terrell Mayes was fired from around the corner and half a block away. The investigation into the homicide continued Wednesday; there have been no arrests.

Even the 278 confirmed gunshot reports recorded by Minneapolis police is probably low, said spokesman Sgt. William Palmer. Paperwork doesn't always include the gunshot report if a more serious crime was committed, he explained.

And people report hearing thousands more gunshots on city streets. Police have recorded some 2,300 reports so far this year from people who believe they heard a weapon being fired, said police spokesman Palmer. Officers respond to every call, though many times those sounds turn out to be something else -- a firework, a car backfiring, a snowplow hitting a manhole cover -- or simply a misguided celebration.

Deputy Chief Rob Allen said all reports of gunfire are serious, even if sometimes the bullets aren't aimed at anyone.

"The problem with people shooting, even if they're not shooting at anyone, is that that bullet comes down somewhere," he said. "It can very easily kill somebody."

It may have nearly happened again Wednesday in St. Paul, where police are scrambling to unravel the shooting of a teenage boy in the leg on a busy St. Paul street corner. The boy survived, and it's not yet known if he was the intended target, a police spokesman said.

Progress against illegal guns

Hennepin County Attorney Mike Freeman, who had planned to announce on Wednesday that a yearlong program to get guns off the street had made significant progress, said the toddler's death had cast a pall over those accomplishments.

"Folks say you're supposed to treat every case the same. We can't. We won't." said Freeman. "Every one of us is just sickened by this."

The news conference was called to tout a crackdown on gun-carrying felons, and the resulting increase in charges and convictions for gun crimes last year.

Instead, talk quickly turned to how, if ever, the shooter responsible for Terrell's death would be brought to justice. Freeman said it was too early to say whether the shooter could be charged with murder.

Freeman said more aggressive efforts to arrest and convict criminals who use guns is an important step to prevent more tragedies like the shootings that killed Terrell Mayes earlier this week and 11-year-old Tyesha Edwards in 2002.

Project Exile, the effort Freeman launched in collaboration with federal prosecutors in July 2010, charged 286 gun cases in Hennepin County in its first full year. That was up from 251 in the previous 12 months. The number of convictions rose 17 percent, from 212 to 256.

Of those 286 cases, 17 were charged in federal court, where sentences are often longer and don't permit parole. In state courts, a felon in possession of a firearm conviction carries a five-year mandatory minimum sentence.

In Hennepin County District Court next week, 34-year-old Darryl Donail Walker of Minneapolis could face up to 15 years in prison following a conviction for fifth-degree drug possession and illegally possessing a firearm. Walker, a convicted felon, was spotted tossing a gun out the window of his north Minneapolis home while police searched for drugs last May. A jury found Walker guilty and a danger to public safety, which will allow a judge to impose a longer sentence.

In another case, Keegan Jamaal Rolenc, an alleged member of the TreTre street gang, was charged with eight felonies, including drive-by shooting, second-degree assault and prohibited person in possession of a firearm for allegedly firing at an occupied home and a car. The multiple felony charges are a result of stepped-up prosecutions in hopes of securing a longer prison sentence for Rolenc, said Hennepin County Attorney spokesman Chuck Laszewski.

Gunplay like the allegations brought against Rolenc is exactly what may be responsible for the deaths of innocent victims like Terrell, Freeman said.

"You can't make a priority of every single one of the 10,000-plus crimes that come in here," Freeman said. "But when you look at the ones that we believe, and history shows us, cause the most misery in the neighborhoods, I think it's guns. And it's gunfire that tragically killed this young man."

St. Paul shooting

Wednesday's shooting in St. Paul occurred just before 3 p.m. at the corner of Arcade Street and Maryland Avenue E. while several teenagers were in the area, witnesses said. The area includes a CVS, Walgreens, Burger King restaurant and busy bus stops.

St. Paul police spokesman Howie Padilla said that the male victim showed up at Regions Hospital with injuries that were not life-threatening. There were no arrests as of Wednesday evening and no suspect description.

Symone Freeman, 18, said that large groups of teenagers often congregate on the corner, where she regularly catches a bus.

"That's scary," Freeman said when she learned of the shooting. "Who gets shot in broad daylight?"

Staff Writer Chao Xiong contributed to this report. • 612-673-4921 • 612-673-7329