Froome and yellow jersey wearer Thomas were among them, with the champion suffering cuts to his lower back.
Italian Sonny Colbrelli punched first but it was Kittel who hit the thrusters, edging out Démare to win his 10th Tour de France stage, an accomplishment that moved him to tears.
Romain Bardet, the Frenchman who finished second overall behind Froome last year, and seven-time Grand Tour champion Alberto Contador lost even more time.
Groenewegen was joined by team-mates Primoz Roglic and George Bennett on the deck - the latter's fall and subsequent bike replacement leading to his mechanic almost slipping over when giving him a push off.
'Bubble pads' - small raised dots - featured on the upper arms of several Sky riders' jerseys.
"I am so happy that I got this victory today", Kittel said.
"Chris Froome has already secured his place in history but he is closing in quickly on great". But they were greeted with wet weather which didn't show, Germany's 6th largest city at it's best.
Although the race jury said there was nothing illegal, at least two teams complained, saying there was an obvious gain in aerodynamics.
"I just can't believe it", Thomas said.
Despite the rain, fans under umbrellas turned out in large numbers lining the entire route as the Tour's start returned to Germany for the first time in 30 years.
So as there was nowhere for me to go either amidst the mayhem, I came down too; albeit I was pretty lucky to land on top of one of my BMC Racing teammates than the road.
Michael Matthews (Sunweb) finished ninth on the stage.
I was in the middle of the peloton that was chasing a breakaway nearing Liege when we turned right and into a roundabout.
On to the real stuff. He's the first cyclist from Wales to wear the leader's jersey. Kuznetsov, a 25-year-old Russian, will count $7.8 million against the salary cap through the 2024-2025 season. "There's a hope he will ride himself into fitness during the race and start challenging for wins in the second half", he said.
Taylor Phinney (Cannondale-Drapac), Thomas Boudat (Direct Energie), Laurent Pichon (Fortuneo-Oscaro) and Yoann Offredo (Wanty-Gobert) were never allowed to establish a large lead, but for a while it looked like Tour de France debutants Phinney and Offredo might defy the odds and avoid capture. Just look back to Greg LeMond's use of triathlon bars in 1989, and Francesco Moser's disc wheels in 1984. If that prompts debate, so much the better. Anything can happen and I wouldn't take anything for granted. Price's new contract begins in 2018-2019 and runs through 2025-2026.
The three-week Tour concludes in Paris on July 23.
With a 10-second bonus, Kittel is third overall, six seconds behind Thomas. The auction site Lelands.com reports that the ball sold Saturday for $403,657.20. "But I think it's good that they have the pressure".