According to the Hong Kong's South China Morning Post and other local media outlets, the female demonstrator was shot on Sunday by police in her right eye.
Witnesses say she was hit by a bean-bag round, and local media reported she may lose an eye.
Hong Kong police rules state such non-lethal ammunition should be shot at people's body or limbs, not at their head.
The police overreaction sparked huge protests on Monday, as thousands of demonstrators took to Hong Kong International Airport to protest the police takedown.
Their presence forced the airport to declare its temporary shutdown from Monday at 4:30 p.m. to 6 a.m. Tuesday, local time.
The shutdown caused more than a hundred flights to be cancelled, including those between Hong Kong and South Korea.
South Korea's transport ministry says 23 flights were scheduled during the shutdown period, with ten cancelled and the others likely to be so as well.
The ministry estimates around a thousand people staying at Hong Kong airport on their way to South Korea are grounded, and the number could increase, especially if the rallies continue into Tuesday.
The ministry added those people could get on flights when the airport reopens on Tuesday.
If that doesn't happen, it's preparing to fly them to South Korea using regional airports in mainland China.
Choi Si-young, Arirang News.