Nearly 100,000 marijuana plants were found growing at four illegal farms in the San Bernardino National Forest, authorities said Tuesday.

Investigators on Thursday found almost 59,000 marijuana plants growing in a canyon above Arrowhead Springs and more than 5,000 plants in a canyon near Rim Forest.

The next day, they discovered more than 32,000 plants in Lytle Creek Canyon and 3,000 in the Miller Narrows area.

No arrests have been made, said officials with the San Bernardino County Sheriff's Department and the U.S. Forest Service.

-- Tony Barboza