Two Minneapolis men died as a result of the tornado that swept through the area Sunday.
Floyd David Whitfield, 59, was killed in his vehicle when a tree went through his front windshield.
Rob MacIntyre, 54, died Sunday while trying to help his neighbors. Friends say he collapsed while trying to clear debris with his tractor.
MacIntyre was renowned for his work with raptors such as peregrine falcons.
A friend of MacIntyre's, John David, says MacIntyre lost every tree he'd carefully tended on his north Minneapolis property in Sunday's storm, but he wanted to check to see how his neighbors were doing.
He asked David to meet him with 20 sheets of plywood, so they could board up damaged windows. But the two friends wouldn't see each other again.
"He pulled out his chain saw and cut his way out of the driveway, and got his tractor out and went to start helping people in the neighborhood," said David. "He went door to door, making sure everybody was OK to see if anybody needed help. When he found out everybody was OK, he started pulling things with his tractor."
David says friends don't know the exact cause of death yet, but they believe MacIntyre suffered a massive heart attack.
MacIntyre had spent decades trying to restore the population of peregrine falcons in Mississippi River Bluff country. As president of the Raptor Resource Project, MacIntrye had worked to release falcons and monitor their high nesting spots.
In 2003, he installed his first camera in an eagle's nest in Colorado. One of his inventions was a special camera mounted on the back of a raptor that was featured in a PBS Nature documentary called "Raptor Force."
In an interview on the PBS website, MacIntyre called falconers like himself "a bunch of nuts. I think every single one of us is born with a neuron that is not connected correctly."
Longtime friend and colleague Bob Anderson, the executive director of the Raptor Resource Project, said that trait helped MacIntryre attempt novel things to help the birds.
"We called him the mad scientist because ... when people said it couldn't be done, he looked at it as a challenge, and he often did things that a lot of people couldn't do or said that was impossible to do," said Anderson. "Probably one of his biggest contributions too was actually helping us with innovative releases to get falcons back on Mississippi cliffs."
Anderson says MacIntyre will always be known for helping people.
"In fact, he died helping neighbors in the aftermath of yesterday's tornadoes. Rob was a giving soul," said Anderson.
Rob MacIntyre leaves behind his wife Jan, other relatives and many friends.