Three Fullerton high schools were on lockdown Thursday as police investigated bomb threats.

The schools affected were Sunny Hills High School, 1801 Lancer Way; Troy High School, 2200 E. Dorothy Lane; and Fullerton Union High School, 201 E. Chapman Ave.

The first threat came in about 1:25 p.m. Thursday, followed by the other two, said Fullerton police Officer Kristy Wells.

The schools were locked down “as a precaution,” Wells said.

The public was encouraged to remain clear of the schools as police investigate, Wells said.