A gunman killed six members of his family, then took his own life, during a spate of shootings on Monday in the eastern Iowa city of Muscatine, a waterfront town situated across the Mississippi River from Illinois, police said.

A preliminary investigation into the gun violence indicated the shootings "stemmed from a domestic-related dispute," the Muscatine Police Department said in a statement, although no mention was made of precisely what may have precipitated the bloodshed.

Four of the victims were found shot to death inside a residence by police officers responding to the first reports of gunfire shortly after noon local time.

Although the suspected killer had fled the scene before officers arrived, he was quickly identified as Ryan Willis McFarland, 52, of Muscatine, and was located on the city's riverfront trail near a pedestrian bridge, Police chief Anthony Kies said during a news briefing.

While officers were talking with him, he took his own life, police said.

After information surfaced indicating there may have been additional victims, police found the bodies of two other men McFarland was believed to have shot - one in a nearby residence on Mill Street and another at a business on Grandview Avenue.

All the victims were believed to be family members of the gunman, Kies said. They were not publicly identified. An ABC television affiliate reported that at least two of the victims were children.

"Today I simply do not have the words -- this act of evil and what it has done to our community," Muscatine Police Chief Anthony Kies said at a press briefing Monday a sreported by ABC News.

The police chief told reporters that McFarland had a previous criminal record, but he declined to elaborate. Authorities have not mentioned the names or the ages of those who have been shot by the gunman. Muscatine, a city of about 24,000 people, is the county seat of Muscatine County and lies about 155 miles east of Iowa's state capital, Des Moines.