Child-care providers operating out of their homes have been cited for gun-related violations at least 20 times since 2006, according to records reviewed by the Star Tribune.

The tally is another measure of the regulatory gap in Minnesota between home-based and center-based care.

At a home in Bloomington last June, for example, children witnessed a relative of the provider wield a gun during a violent argument; a St. Paul day care provider pulled a gun in 2008 and threatened a person at her home; a child at a Duluth home reportedly used a gun in 2006 to make threats toward another child.

At Minnesota's 1,500 licensed child-care centers, guns are banned. Violators can face felony prosecution, with up to five years in prison and a $10,000 fine. The last known gun incident at center-based care occurred in 2004, according to the state Department of Human Services (DHS).

At home-based day care, by contrast, guns are restricted during business hours and must be unloaded and locked away. Penalties are uneven. Some providers who leave guns accessible in their homes are given correction orders but no fines.

In addition, parents who depend on licensed in- home providers are often in the dark about the presence of firearms because state law does not require providers to disclose whether they have guns in their homes.

"There are people who ... very strongly defend that right to have a gun in their home," said DHS Inspector General Jerry Kerber. "From our perspective, if they are going to have a gun in their home while they are providing child care, they absolutely must do it in a safe manner."

Several incidents uncovered by a Star Tribune investigation involved family members or acquaintances of the day care provider. In a 2008 incident at a Lakeville home, someone living at the provider's home set off an improvised explosive device that partially tore off two of the person's fingers. When police arrived at the home after the 4 a.m. blast, they discovered bomb-making materials and a shotgun.

Many of the violations involve providers who leave guns accessible to children. In 2010, a day care provider in Hector, Minn., left a gun propped against the wall of a bedroom where children slept. A provider in a Bloomington home was cited in 2008 and again in 2010 for leaving guns accessible to children in her garage.

Three states — Michigan, Massachusetts and Pennsylvania — require in- home providers to notify parents if there are guns in the house, according to a 2008 study by the National Association for Regulatory Administration.

Kerber said his agency will review Minnesota's disclosure policies after questions were raised by the Star Tribune.

Staff writer Glenn Howatt contributed to this story.