Cyclists will take to the streets today in reaction to the incident, where 16 people were badly hurt. Warning: this video footage may upset some viewers

A protest march will be held in Porto Alegre in Brazil this evening after a driver ran down dozens of cyclists at a Critical Mass ride on Friday.

The incident was caught clearly on several cameras and the footage makes for disturbing viewing.

One witness wrote on the local Critical Mass blog: "I saw legs in the air, helmets, bicycles, arms, all mixed together with parts of the car all flying and making noise. It was like a horror movie."

Incredibly, although 16 people were badly injured, nobody was killed.

The driver, Ricardo Neis, 47, handed himself in to police on Monday. His abandoned and badly damaged car had been found on Saturday morning.

Neis' lawyer claims he was acting in self-defence after a group of riders who threatened to overturn his carEven ifthis is true he appeared to have made a barbaric overreaction.

I spoke to Marcelo Guidoux Kalil, one of the 120 cyclists at Friday's ride.

"There was an impatient driver behind the group, in a black VW Golf, who wanted to go faster," he said. "Some of the participants of the ride went to talk to the driver and ask for patience. The man than started threatening them, accelerating the car and pushing some bikes with it.

"Then he accelerated all he could as you can see in several videos.

"He ran over more than 20 cyclists, injuring dozens, of which four were severe; breaking bones, bleeding heads and losing consciousness. He then ran away."

It is not clear what Neis will be charged with. But riders and some local media are urging the Ministério Público, the Brazilian equivalent to the crown prosecution service, to push for attempted murder.

Protesters dressed in white will march through the city tonight in reaction to the incident, and they say the next Critical Mass will be the largest ever, as cyclists from São Paulo and other nearby cities plan to attend.

Critical Mass rides are held on the last Friday of every month in more than 300 countries around the world, including many cities in the UK.

There is no official organisation behind it, but most agree it is intended to show that cyclists are not a troublesome nuisance to traffic, but a legitimate part of it.

By grouping together in their dozens or hundreds they can dominate the roads for an evening.

Cyclists in Porto Alegre have little in the way of cycle lanes and face far more dangerous traffic than in the UK.

Events from within the cycling community have sprung up in response to Critical Mass, such as Critical Manners and RideCivil, where riders obey all traffic laws and attempt to make peace with drivers.

However, many people question whether deliberately bringing traffic to a standstill is the best way to make a statement, or if it risks antagonising and alienating drivers.

But whether or not Critical Mass is the right way to go about promoting rights for cyclists is largely beside the point – anyone who appears to display such disregard for human life should never be let behind the wheel of a car.