Vandals burned the letters CC into the Western High football field and painted the words "Cypress High" along with obscenities around the school before Cypress' 27-6 loss at Western on Friday.
Lt. Ted Labahn of the Anaheim Police Department said there were no suspects, although a witness heard someone yell "Cypress" just after midnight Friday morning. If suspects are found, the Anaheim school district could press criminal charges of malicious mischief. It probably would be a misdemeanor offense.
Cypress officials are investigating the matter, but did not want to comment about the incident.
Moments of silence are becoming increasingly commonplace at high school events; Thursday, it was at Villa Park, where former three-sport letterman Justin Willson was remembered.
Willson, who had been in a coma about five weeks, died Wednesday. He graduated in June.
Although a coroner's report is pending, Villa Park Principal Daniel Burch said he was told Willson had contracted a virus that attacks the brain.
"He was having brain seizures," Burch said. "He was put into a coma at the hospital to try to control them, and he never came out of it."
A crowd of about 1,500 observed a minute of silence in his honor at halftime of Villa Park's 20-14 victory over Brea Olinda.
Willson lettered in three sports while attending Villa Park: basketball, wrestling and football, though he didn't play football last year.
The school's Key Club is accepting donations on behalf of the family, Burch said.
Three Huntington Beach volleyball players, Melissa Wendt, Allison Ciarelli and Jill Meyers, were named to the all-tournament team after the Oilers won the Orange County/Southern California Division I championship Saturday at Edison High.
The rest of the Division I all-tournament team was San Clemente's Kate Metzger and Wendy Wilkins; Dana Hills' Jami Bari and Megan Degeus; Corona del Mar's Kelly Campbell; Laguna Beach's Michelle Christ; Mater Dei's Roberta Gehlke, and Newport Harbor's Jeannette Hecker.
Ocean View won the tournament's Division II title on its home court.
The Division II all-tournament team included Ocean View's Katie Lindquist and Shelby Jameson; Katella's Kelly Alua; Cypress' Michelle Woiemberghe; and Sunny Hills' Taryn Catlin.
The Villa Park water polo team had a milestone week, first giving Coach Jeff Ehrlich his 400th water polo victory at the school and then winning its first tournament since 1982.
After a 7-6 victory over North Hollywood Harvard-Westlake in the title game of the Long Beach Millikan tournament, Ehrlich is 404-140 in 22 seasons with the Spartans.
"I think the first reaction for a lot of people is, 'Man, you've been in this business a long time,' " Ehrlich said.
Times staff writers Martin Beck and Paul McLeod contributed to this story.