'Running of the Balls' gone wrong: Contestants crushed by 660-pound object

It doesn’t weigh nearly as much as a bull – but it apparently packs just as hard of a punch.

Two men sprinting down a Spanish town’s streets during its animal-friendly “Running over the balls” event were left with serious injuries after the 660-pound resin object flattened them along the course.

One of the shocking incidents in Mataelpino, north of Madrid, was captured on camera Saturday and shows a man trapped against a fence as the 9-foot-high ball careens toward him. The white ball with a bull painted on its front – which can reach speeds up to 20 mph -- then smashes into the man, forcing him to hit his head on the street.

The man is reported to have suffered a fractured skull and is still hospitalized and in a coma, while another man was released after being treated for three broken ribs and a concussion, The Telegraph reported, citing local media.

“We are going to review all of our security measures and boost the information given out because people have started coming here from all over the world. We don’t want this to become a tragic event, but rather something fun,” Mayor Pérez de los Nietos told El País, a Spanish newspaper.

SPANISH TOWNS BUCK TRADITION WITH 'RUNNING OF THE BALLS' EVENTS

“People who are used to bulls know that they can’t just stand still in front of them because they could be gored. But with the ball some people think that nothing will happen to them, but this is not the case. If they get a direct hit, it can be serious,” he added.

The town started the event in 2011 as a cost-effective replacement to the traditional livestock Running of the Bulls events across Spain, and has received praise from animal rights groups such as PETA.