Burnsville police and the Hennepin County medical examiner's office are investigating the death of a 4-year-old boy Tuesday in the 30 block of Horizon Heights Road in Burnsville, near Hwy. 13 and County Road 11.

Police spokesman Sgt. Rory Bochniak said police and paramedics were called to the boy's home, where he lived with his mother, about 5 p.m. Tuesday on a report of "medical problems." The boy was dead when they arrived, Bochniak said. He did not know the exact nature of the medical problems or the cause of the boy's death.

The mother's boyfriend, 24, was arrested near the scene Tuesday and is the only suspect in the case. Police Chief Eric Gieseke said whatever transpired in the home was an isolated domestic incident with no ongoing threat to the community. The man has not been charged in the boy's death, but he has been charged in Dakota County with several other felonies, including violating an order for protection and criminal damage to property. The man is being held in the Dakota County jail in lieu of $50,000 bail.

The boy's name has not been released.

Bochniak said the boy and his mother moved to Burnsville in April. He didn't know where they lived previously. There have been no other police contacts with them.

The boy's death has not been ruled a homicide. The investigation "is going to be lengthy," Bochniak said.

"We're dealing with a young child," he said. "Obviously, you grieve for the family. It's difficult, but it will take time. It's not something you can do overnight."

PAT PHEIFER