The main suspect in a killing spree in Florida that left his wife, a church pastor and neighbour dead has reportedly confessed.

A police affidavit released on Monday said Andres 'Andy' Avalos had confessed to the killings of 33-year-old Amber Avalos, her friend, 46-year-old Denise Potter, and church pastor, 31-year-old James 'Tripp' Battle.

The killing spree occurred on Thursday in Bradenton, around 45 miles south of Tampa.  After a manhunt was launched, Avalos was tracked down to a mobile home park and arrested on Saturday.  He has been charged with all three murders.  

Investigators at Manatee County Sheriff's Office said the Avaloses' 4-year-old son was at home at the time his mother and her friend were slain. 

The affidavit revealed Amber Avalos had suffered a gunshot wound to the chest and severe injuries to her face, and was found by officers hanging from a cord in the laundry room. 

Potter was found lying in a hallway and had multiple gunshot wounds. 

It was not clear from the document whether the child had directly witnessed the killings but he did tell police that his father was the only other person home at the time.  

Investigators believe Avalos killed his wife and her friend first before going to Bayshore Baptist Church, where his wife led the children's ministry.  There he encountered Joy Battle, church secretary and the pastor's wife, and apparently spent around 20 minutes "rambling on about how the world was evil", she told officers. 

Avalos reportedly confronted the pastor outside the church and Joy Battle saw him fall to the ground after hearing gunshots. 

At the morning service on Sunday, Joy Battle said she would continue believing in Jesus despite the tragedy of losing her husband. 

"You can silence the voice, but you can't silence the song," she said. 

"You can bury the horse but the work will go on.  I will grieve the rest of my days, but I will stay together because I know Jesus.  He is the song and the work." 

According to AP, Avalos is being held in the Manatee County Jail without bond and has requested a public defender.