YOSEMITE NATIONAL PARK, CALIF. -- Vandals last month used spray paint to draw on more than 30 sites at California's Yosemite National Park, officials said.

Park officials are asking anyone who was on the trail to the top of Yosemite Falls on May 20 and who saw people carrying cans of spray paint and tagging the area to contact the National Park Service.

Vandals used white and blue spray paint to draw on boulders and other sites along the Yosemite Falls Trail, park officials said in a Facebook post Sunday.

At approximately 8:15 p.m. on May 20, park rangers received multiple reports of vandalism along the trail. When they assessed the damage the next day, they found more than two dozen places where graffiti had been spray-painted, officials said.

Photos posted on social media show rocks tagged with the word "Fresno" and other illegible writings.

The smallest graffiti measured one foot by one foot (30 centimetres by 30 centimetres), but most were three feet by three feet (one metre by one metre), and a few were larger than eight feet by eight feet (2.5 metres by 2.5 metres), officials said.