As scuffles broke out in front of the National Assembly and French police responded with tear gas, paramedics huddled around the injured protester at the National Assembly gates.
They have since broadened into a revolt against the President, Emmanuel Macron, and a political class seen as out of touch with common people.
There were more violent clashes in France on Saturday as the Yellow Vest protest movement entered its thirteenth week.
Today, there have been more clashes between riot police and protestors on the street, with tear gas and grenades deployed.
Volunteer medics at the National Assembly said that a man had had his hand ripped off during the clashes between police and protesters.
Royer said the victim was a yellow jacket photographer "taking photos of people trying to break down the barriers protecting the entrance to the National Assembly", at around midday.
Anarchists and supporters of extremist groups on the far-Right and far-Left often join the "yellow vest" protests, along with troublemakers known as "casseurs" intent on causing as much damage as possible.
"He wanted to bat it away so it didn't explode by his leg - and it went off when he touched it", he added.
One protestor lost four fingers witnesses said he'd tried to handle a sting-ball grenade thrown by police.
"This is the second severe injury in as many weeks and will likely inflame tensions between the government and the yellow vest movement", Beardsley reported.
Protests also took place in other French cities, including Marseille, Montpellier, Bordeaux and Toulouse, the BBC noted.
Police said 31 protesters were arrested on Saturday but the AP reports France's Interior Ministry said this week's protest was significantly smaller than last week's.
But a YouGov poll of 1,037 people issued on Thursday suggested that almost two out of three people in France (64 per cent) still support the movement.