The horrific attack unfolded just after 2 p.m. on Saturday in San Vicente, near Ensenada, on the Pacific coast of the Baja Peninsula, the Reuters news agency reported.

The violence erupted during the last day of a two-day all-terrain car rally, local officials said. Video purportedly of the shooting was posted on social media, showing off-road vehicles lined up along a road and capturing the sounds of screams and numerous rounds of gunfire.

Several people who appeared to have been shot were seen in the online footage lying on the ground.

Multiple shooters wielding rifles emerged from at least two gray vans at a gas station and opened fire on participants of the car rally gathered there, according to Reuters, citing 911 calls.

Following the volley of gunshots, the perpetrators got back in the vans and fled the scene, which is about 86 miles from San Diego, California, according to Reuters.

There were no reports of any arrests being made.

Ensenada Mayor Armando Ayala Robles said state Attorney General Ricardo Ivan Carpio Sanchez commissioned a special group to investigate the massacre.