(CNN) -- A fierce weather system -- featuring baseball-sized hail and multiple tornadoes -- ripped through Colorado on Wednesday afternoon, spurring warnings to people in and around Denver to take cover.
The frenzy was tied to a dangerous super cell thunderstorm that, in addition to heaps of hail, produced a number of twisters, according to storm chasers on the scene.
The National Weather Service said there were reported tornado touchdowns in Watkins, East Denver, Aurora, Byers and Leader. One witness, Jeff Piotrowski, said shortly after 3 p.m. (5 p.m. ET) that he had personally seen five tornadoes on the ground not far from Denver International Airport.
"This thing is spinning up multiple tornadoes," Piotrowski told CNN's Wolf Blitzer. "There were tornadoes on the outer ring of the circulation, ... and then there's the main tornado vortex closer to the storm."
One of those got within about a mile of the Denver airport, only to move past it, according to Piotrowski.
The airport wasn't struck directly, though it was certainly affected.
Six planes in Denver-based Frontier Airlines' fleet had to be taken out of service due to hail damage, company spokeswoman Kate O'Malley said.
And the airport's Twitter feed reported 38 flights were diverted and average delays of 90 minutes, not to mention the ordeal of removing hail and water from the airfield.
While those delays subsided, by later Wednesday night travelers were dealing with a different problem: Sections of Tower Road and nearby streets were closed due to flooding, according to a Commerce City press release.
Likewise, the city of Denver and neighboring municipalities appear to have escaped without significant damage. The heart of the system then moved into more rural areas.
Even if these areas escape without severe wind damage, the hail -- some as big as baseballs, according to storm chaser Mark "Storm" Farnik -- made an impact in more ways than one.
The weather service's Boulder branch retweeted a photo of about 6 inches of accumulated hail in Denver's Green Valley Ranch, plus another showing Highway 470 restricted to one lane because of the hard, white stuff.
For most of the evening, much of northern Colorado -- as well as several counties in Wyoming -- were under tornado watches. Those advisories later expired.
The storms continued to produce heavy rain and relatively small hail that contributed to minor street flooding in places like Boulder, Loveland and Fort Collins, according to the National Weather Service.