A lawsuit targeting electric scooter-sharing companies seizes on the dangers of zipping around town on two wheels and brings gory detail to one of the more polarizing technology trends to emerge over the last year.


Nine people who were injured by electric scooters filed the class-action suit on Oct. 19 in Los Angeles County Superior Court. It accuses startups Bird Rides Inc. and Lime — as well as their manufacturers Xiaomi Corp. and Segway Inc. — of gross negligence, claiming the companies knew the scooters were dangerous and deployed them in a way that was certain to cause injuries.


Since e-scooters zoomed into the U.S. last September with the arrival of Bird, hundreds of riders and pedestrians have landed in the hospital with injuries ranging from severe gravel rash to knocked-out teeth, ripped out toenails and detached biceps, according to doctors and victims.


Last month, three people died while riding scooters in Dallas, Cleveland and Washington D.C.


There is no official tally on the number of scooter-related injuries in the country since hospitals code their patients based on the type of injury they are admitted with, rather than what caused it. But one metric Bird and Lime have been closely tracking is the number of rides their scooters have handled: more than 20 million combined — and growing everyday.


Electric scooters have appeared in more than 100 cities worldwide with the startups aiming to usher in a new, environmentally friendly era of micro transportation. After a remarkable one-year ascent, Bird and Lime are now two of the youngest startups to earn unicorn status in Silicon Valley with valuations of $2 billion and $3 billion or more, respectively.


The rapid rise of the scooter revolution has been plagued by controversy, complaints and concussions. Citing fears over public safety, officials in some cities, including San Francisco and Santa Monica, have temporarily banned electric scooters and filed criminal complaints against the companies behind them for operating without a business permit. Some frustrated vigilante residents have tossed scooters into the ocean, buried them in the sand and even set them on fire.


According to the lawsuit, two of the plaintiffs were injured by tripping over scooters left discarded on the sidewalk, four were rammed into from behind as they walked, including a 7-year-old boy who suffered severe damage to eight of his front teeth and had to get his lip stitched back together.


“These companies are putting profit over safety,” Catherine Lerer, the personal injury lawyer at McGee Lerer who represents the plaintiffs, said in an interview for Bloomberg’s Decrypted podcast.


Since filing the lawsuit, Lerer said an additional 75 people who have suffered from scooter injuries have contacted her, including a 67-year-old man with a brain injury.


Bird and Lime say safety is a top priority. But from their perspective, cars are the real transportation danger.


“Class action attorneys with a real interest in improving transportation safety should be focused on reducing the 40,000 deaths caused by cars every year in the U.S.,” a Bird spokesperson said in a written statement.