UPDATE (WKOW) -- An update from Sheriff Mark Rohloff says the two young people who died in the crash were a boy, 13, and a girl,17. The pilot was the teens' grandmother and the other woman was their mom. No names have been released.
Green County Sheriff Mark Rohloff said the pilot was familiar with the airport and had flown there before.
"We're very sorry for the loss. We understand there's some attachment to family here in Monroe. Will do our utmost to assist in the investigation. Will be having people staged at the scene throughout the night," he said.
UPDATE (WKOW) -- At a news conference Sunday afternoon, Green County Wisconsin Sheriff Mark Rohloff said the four people who died in the crash were all family members who were flying in from Kenosha to Monroe.
He believes they were all adults: the pilot was a grandmother and it was her daughter and two granddaughters who were on board. One of the granddaughters may have been close to 18-years-old. Other relatives reportedly also live in the Monroe area.
Rohloff says the sheriff's department will act as a liaison to the family members, seeing what services they can offer.
The sheriff said a call to 9-1-1 came in a little after 12 noon that the plane was losing power. It landed in an open field north of the airport a short time later. The sheriff say the plane "landed hard," and was completely engulfed in flames when it hit the ground.
He added that the crash site is hilly, "It's an area of grassy meadows and rather rolling hills. The site was right against the tree line."
The airport manager was involved right away to make sure certain protocols were in place to preserve the scene.
Sheriff Rohloff wouldn't speculate about what happened to cause the crash. He said his department, along with the Federal Aviation Authority and the National Transportation Safety Board will be continuing the investigation.
The sheriff added that, "At this time the area is secured with no traffic allowed and the roadway is closed."