Woman, 25, fatally shot in the neck while driving on Iowa highway

A 25-year-old woman was shot and killed on an Iowa highway and police are looking for the gunman who fired the fatal shot.

Micalla Rettinger was on her way home from work, driving on Highway 218 from Cedar Rapids to Waterloo, when her car was struck by a single gunshot, the Waterloo Police said.

The bullet went into her window, fatally hitting Rettinger in the neck, police said.

A passenger, 32-year-old Adam Kimball, was also struck and seriously injured, Waterloo Police spokesman Major Joe Leibold told ABC News.

A third person in the car survived uninjured, police said.

It's not clear where the bullet come from, Leibold said.

Rettinger was a 2016 graduate of the University of Northern Iowa, where she earned a degree in biology and was "an outstanding outfielder" for the softball team, the university said.

"We are devastated to learn of the senseless death of Micalla Rettinger," the university's director of athletics, David Harris, said in a statement. "This news is heartbreaking to our softball team, UNI Athletics and the entire campus. Our thoughts and prayers are with Micalla's family and friends."

"I can still see the smile on her face and I remember the way she always thought of other people first in a genuine way," softball coach Ryan Jacobs said in a statement. "When we had youth camps, she was the one that all of the kids on campus would be drawn to. This is a huge loss to our team and everyone that knew her."

No one has been arrested, Leibold said, and he would not say if police have suspects in mind.

"There is nothing to indicate the victims in this case were in anyway involved in any activity that would have caused them to be targeted in this manner," police said in a statement on Monday.

Anyone with information is urged to contact the Waterloo police at 319-291-4340 Option 7.

A $5,000 reward for information has been offered.