Video (00:45) : A sheriff in northwestern Wisconsin says the shooter who killed four people and wounded two others in two nearby communities was found dead when deputies responded to an initial call about a shooting in Lake Hallie.

– A day after police found five people shot to death at two houses near this central Wisconsin city, a man who said he was the father of the shooter said he had no idea what precipitated the violence.

“I lost two sons and a grandson,” said Ritchie German Sr., of North Prairie, Wis., who learned the news when police called him Monday morning.

Among the dead, according to German, are his adult sons Ritchie Jr. and Douglas, and Douglas’ son, Calvin, 8.

Authorities suspect Ritchie Jr. was responsible for Sunday’s killings, German said.

He indicated that his son has struggled with mental illness but doesn’t know where he got the firearm used in the shootings, or why he apparently turned it on his brother, mother and nephew at a Lafayette, Wis., townhouse as well as three other people at a house four miles away in Lake Hallie. Two people there were found dead, including Ritchie, Jr.; two others were wounded.

It wasn’t immediately clear if Ritchie Jr. shot himself or died some other way. Authorities did not name anyone involved or release the conditions on the two injured but did confirm that the shooter was among the dead.

Lake Hallie police and the Wisconsin State Patrol investigated Monday the scene of a shooting that left two dead and two in the hospital. Three people were found dead at another location.

Chippewa County Sheriff James Kowalczyk said he planned to hold a news conference Tuesday morning.

German called the news a shock. He said he has been estranged from his family since he divorced his wife, Bridget, in 2015.

He said Ritchie Jr. was mostly unemployed for the last several years. He lived with his father from 2005 to 2014 and worked for just one year during that time at a Menards warehouse.

The son lived in his bedroom most of the time, said Ritchie Sr., who thinks his son had bipolar disorder and schizophrenia.

“I told his mother to get him help,” said Ritchie Sr. He believes Bridget was also killed in the shootings.

His son had one other incident with a gun, in about 2005 or 2006, when he pulled a shotgun on another brother. No one was shot in that confrontation, and Ritchie Jr. was taken to jail. Ritchie Sr. said he was working on the road at the time as a long-distance trucker, and bailed his son out when he returned home. Ritchie Jr. was sentenced to probation, he said.

In a statement released Monday morning, Kowalczyk said a 911 call alerted police to gunshots at the Lake Hallie home about 10:30 p.m. Sunday. Several hours later, police went to the German family’s Lafayette townhouse to tell them about the gunman’s death and discovered three more bodies there.

Even Ritchie Sr. said he didn’t understand the connections between the shootings at the two homes. He said his son Douglas worked for SFR Plastic Extrusions in Cadott, Wis.

Calvin’s mother lives in California and has not been a part of her son’s life for many years, he said.

In Lake Hallie, Gail Solberg lives two doors away from the single-story ranch house where the shootings took place. She said her husband heard a bang Sunday night, but like others in the neighborhood assumed it was a firecracker.

“We’ve had so much fireworks going off,” she said. She said she didn’t know the family well, but often saw a young girl who lived there out playing with other kids in the neighborhood, and sometimes saw a teenage boy from the house waiting at a nearby bus stop. “They were real family-oriented,” she said.

On Sunday night, police told neighbors in the Lake Hallie neighborhood to stay in their houses while authorities searched the area. “They were checking the backyard, shining a light around,” she said. The police strung crime-scene tape around the house, which had several cars parked in the driveway and what looked like two gun blasts through the front screen door.

A woman who lives nearby said her 7-year-old brother often played with Calvin. “Calvin was always a well-dressed kid,” said the neighbor, Hannah Larson. “He was always well-behaved.”

Larson said she learned from the landlord that authorities found Calvin shot to death in his bed. The grandmother, Bridget, was found in the bathroom, she said.

Larson said her younger brother may have had a close call with the incident. He knocked on Calvin’s door earlier Sunday to see if his friend could come outside.

She said the man she knows only as Calvin’s uncle answered the door and said Calvin was visiting his mother. That would have been Ritchie Jr., the suspected gunman.

The Chippewa County Sheriff's Office says this is where three people were found dead in Lafayette, Wis., on Monday.

That surprised Larson’s family, since no one ever spoke about Calvin’s mother, Larson said. “We don’t have any idea why” the shooting happened, she added.