The suspect, Victor Luis Flores, 22, was spotted setting brush fires along the south side of the 91 Freeway, west of a blaze that burned through four acres of brush, officials said.
The Gypsum Fire burned south of the 91 and west of Gypsum Canyon Road, requiring more than 70 firefighters, a helicopter and two air tankers to stop its forward progress.
While crews were fighting the Gypsum Fire, authorities received calls about a man seen lighting brush fires west of the blaze. CHP officers came across Flores, questioned him and ultimately placed him under arrest.
Flores was booked for three counts of arson and was being held on $70,000 bail as well as a $20,000 narcotics warrant. Investigators plan to ask for an increase of bail to $250,000
While Flores was seen lighting fires in the area, officials say the cause of the Gypsum Fire itself has not yet been determined, but it is believed to have been intentionally set.
They are looking for witnesses to come forward. Anyone with information is asked to contact Orange County Crime Stoppers at (855)TIP-OCCS.