Tensions escalated even further in St. Paul's mayoral race Thursday as a political mailer sought to link an increase in shootings in the city with the theft of guns from candidate Melvin Carter's home, and the city's current mayor called for the police union's entire board to step down.

The mailer, arriving at voters' homes this week, proclaims that "St. Paul has a crisis!" and cites crime stats showing a rise in gun violence. It includes the line, "Over 100 shots have been fired since August 15 when Melvin Carter's guns went missing," and says the guns likely would not be on the streets if Carter had called police immediately.

The mailers arrived in homes Thursday, a day after St. Paul Police Federation President Dave Titus apologized for a letter to Carter questioning him about the burglary. Campaign staff for Carter, who is black, have called the letter a "racist attack" and said its mailing — paid for by a group that supports Carter opponent Pat Harris — show the federation's apology was disingenuous.

"The repeated attacks on a family that has been victim to a crime demonstrate again the systemic racism built into police culture across America," Carter's campaign manager Emily Weber said in a statement.

Last week, the Ramsey County attorney's office charged Larobin Scott with one count of first-degree burglary for allegedly breaking into Carter's home in August and stealing items, including two handguns, a video game system and duffel bag with ammunition.

Late Thursday, emotions and rhetoric heated up even further when Mayor Chris Coleman called for the police federation's entire board to resign. "Dave Titus and the board of the Saint Paul Police Federation have embarrassed the good men and women of the Saint Paul Police Department for too long," he said. "The racist attacks and hollow apologies of the last two days may have been aimed at one candidate, but they affect all people of color, and all people of character. ... I am calling on the board of the federation to resign. The time has come for new leadership who understand that their role is to build bridges, not deepen divides."

Coleman's salvo, as well as one earlier by U.S. Rep. Tim Walz, moved the controversy into debate in a statewide race — both Coleman and Walz are running for governor. Also weighing in Thursday on behalf of Carter was U.S. Rep. Keith Ellison and state Rep. Ilhan Omar. All are Democrats.

Minutes after Coleman tweeted his statement Thursday night, Titus fired back: "We appreciate Mayor Coleman's newfound interest in St. Paul after spending so much [time] on his gubernatorial campaign. I only wish he focused that concern on the tragic levels of crime the people he is supposed to represent are dealing with."

Also late Thursday, Harris, whose endorsement by the police federation has plunged him into the heart of the controversy, echoed Coleman's call for the federation's board to step down, saying, "... there is absolutely no place in Saint Paul for the type of dirty, political tactics and dog whistle racism that have come from the Saint Paul Police Federation's leadership over the past few days. It is time for a new direction to truly move all of Saint Paul forward together. I will not stand with the current leadership and call upon the board of the Saint Paul Police Federation to resign."

Of crime and politics

Building a Better St. Paul sent the Thursday mailers, which were printed on a black and red background with images of cracked windows and an intruder entering a home.

The police federation is one of several groups that have donated to Building a Better St. Paul. The group has received $147,900 in donations, including $52,500 from the federation, $40,800 from the St. Paul Area Chamber of Commerce and thousands from other groups, including the firefighters union and Teamsters.

Brian Bergson, who is registered as Building a Better St. Paul's chairman, said in a statement: "Guns and the dramatic increase in gun violence across St. Paul will present critically important challenges for the next Mayor. We believe it should be something voters consider before Election Day."

St. Paul police confirmed that firearms discharges are up 37 percent over the same time frame last year. But statistics also show that reports of weapons being discharged in the city have been rising for years. There were 1,092 reports of weapons being discharged in 2016, up from 862 reports in 2015 and 679 reports in 2014.

DFL State Chair Ken Martin said such last-minute attacks are not uncommon, but the mailers could end up backfiring in the ranked-choice election — where candidates are wary of offending voters who could list them as their second or third choice. Carter and Harris are two of 10 candidates in the race.

"I have no doubt that Pat Harris wasn't involved in it," Martin said. "But his supporters, who were trying to help him, are actually hurting him."

Staff writer Karen Zamora contributed.