Highway Shooting Cases Rise to 20, Kansas City Police Say Authorities say they've linked some of the shootings that have left 3 injured.

April 10, 2014  -- Kansas City, Mo., police revealed today that the number of highway shootings they are investigating has risen to 20 as the hunt continues for suspects.

Authorities said the number had fluctuated because some cases were being added and others were being ruled out through investigative work. Federal agents earlier in the week joined the hunt for a possible spree shooter after three people were wounded.

"I was just driving down the highway and heard a loud noise. Something hit the car, didn't know what it was, so I pulled over at my first opportunity to kind of see if there was any damage and that's when I saw the bullet hole," Tom McFarlane told ABC News affiliate KMBC-TV.

The shootings have occurred along stretches of Interstates 435 and 470 -- some clustered near exit ramps and interchanges. A law enforcement official said Kansas City police had determined that at least some of the recent shooting incidents were linked.

The official would not say how authorities were able to connect the cases. K-9 teams with the Bureau of Alcohol, Tobacco, Firearms and Explosives planned to return to the scenes, looking for ballistics evidence.

In addition, Kansas City police, ATF and FBI have announced a $7,000 reward for info leading to an arrest in the case.

One victim was shot at by someone firing from another car and wearing a ski mask and hood. A woman head a loud noise while she was driving home and was shocked to find a bullet hole in the door next to where her 3-year-old had been sitting.

Two people have been shot in the legs and another in the arm. No one has been killed.

"It's really scary to think that somebody is just out here with no regard to what could happen," said Jennie Baugher, who recently found a bullet hole in her car.

Baugher said she thought she might be victim No. 14.

Ginny Bauer, a Roland Park resident, said she was driving a friend home when her car was hit.

"There wasn't another car in sight and we were in the right lane and hit on the right side," Bauer said.

Authorities said they were determined to find out whether there was a serial shooter in the area. In 2002, a pair of snipers in the Washington, D.C., area paralyzed the region for three weeks, killing 10.

"Anytime you have a random shooter with no reason or mindset behind them that [is] just taking rounds and putting them into cars is causing a problem for everyone," said Rich Marianos, a former ATF assistant director.

Tips continue to come in to police.

ABC News' Jack Date and Pierre Thomas contributed to this story.