The Iowa dad who killed six family members, including two students, before killing himself on Monday was heard screaming a chilling message about money 10 minutes before the horrific killings.

Investigators said Ryan Willis McFarland, 52, perpetrated the domestic violence-fueled massacre across several locations on Monday in Muscatine, close to the Illinois border.

His neighbor, Melissa Weggen, said she heard McFarland yelling in the street around noon.

'I heard him walk by my house, saying "Don't worry about money. Everything goes away when you die,"' Weggen told the Muscatine Journal.

Weggen said that she immediately recognized McFarland and thought he was a 'decent guy.'

'They had yard sales, lots of yard sales, like every weekend,' she said. 'They would walk their pugs past my house all the time. They were always holding hands and they'd have their youngest child with them.'

All of the victims were believed to have been McFarland's relatives. As of Tuesday morning, their identities have not been released by authorities.

McFarland carried out the series of fatal shootings before taking his own life when officers closed in on him near the city's riverfront trail.

Weggen said a massive law enforcement presence showed up on the block roughly 20 minutes after she heard McFarland screaming.

She said the police officers were on loud speakers 'telling someone inside to come out with their hands up.'

After that, Weggen believes she heard one shot fired and said she saw emergency personnel step away from the scene.

Weggen's daughter, Sarah Ziegenhorn, said she graduated high school with one of McFarland's children, his daughter, and that she was 'really sweet.'

'Liked everyone, thought about everyone,' Ziegenhorn, 20, told the outlet. 'She just had a big heart.'

Julia Butters, who lives two houses down from the McFarlands, described the chaotic scene.

'My daughter texted me and said she heard shots and said there were police officers everywhere,' Butters told the outlet.

The scale of the violence sent shockwaves through the close-knit Iowa community, with Muscatine Community School District later saying 'our hearts are broken by this unimaginable loss,' after revealing that two of the victims were students and two others were district employees.

Police were first called to the 200 block of Park Avenue shortly after 12.15pm on Monday following reports of gunfire.

When officers arrived, they discovered four people with gunshot wounds. All four victims were pronounced dead at the scene.

As the investigation expanded, detectives uncovered two additional victims at separate locations in the city.

One man was found in his home and another man was discovered dead inside a business on Grandview Avenue, he said. 

Authorities believe the violence was connected to a domestic dispute.

'While talking to Ryan Willis McFarland, he took his own life,' Muscatine Police Chief Anthony Kies detailed.

'Today I simply do not have the words,' said Kies. 'This act of evil and what it has done to our community.'

Authorities have yet to release the names of the victims and any details about them.

The school district announced that counselors and support services would be available beginning on Tuesday morning at Muscatine High School, Susan Clark Junior High, Madison Elementary, McKinley Elementary and Franklin Elementary.

'Our hearts are broken for the family members, friends, colleagues, classmates, and all those affected by this unimaginable loss. We ask that you keep everyone impacted in your thoughts during this incredibly difficult time,' Superintendent Clint Christopher said.

'We encourage anyone who needs support to take advantage of these resources and to check in with one another. The strength of our district has always been found in the care and compassion we show each other during difficult times.'  

Local politicians also expressed their condolences to everyone affected by the killings.

'We don't know a lot, but we know enough to recognize that this is a tragedy of massive proportions,' wrote State Senator Janice Weiner. 'My heart goes out to the entire Muscatine community - holding them in my thoughts and prayers.

'This tragedy impacts everyone - community, schools, a sense of safety. And community will be needed now more than ever. I hope all who need it will reach out for support.'

Similar thoughts were echoed by Nick Salazar, a Muscatine native and longtime community advocate running for Iowa House District 96. 

'My heart is heavy as our community processes the tragic events that unfolded today in Muscatine,' Salazar wrote. 'My thoughts are with all those affected by this tragedy. Families, neighbors, and first responders.

'Right now, we come together as a community to support one another, check on our loved ones, and keep the victims and their families in our prayers.

'Muscatine is a strong community. We will stand together through this difficult time.'

The city's police department is continuing to investigate the shootings. Officers have asked anyone with information to contact the major crimes unit.

Kies confirmed that McFarland had a criminal record, but wouldn't share any further details.