Rumors of threatened violence surfaced at several Valley schools this week, creating concern and sparking heightened security, but no such incidents occurred, officials said.

Police went on alert after a student was caught with a gun at Central High School, another student was threatened with gun violence at Mt. Whitney High in Visalia, a Clovis Unified student was taken into custody with some components that can be used to make an explosive, and a separate threat was reported at Reedley High School.

Central Unified spokesman Cary Catalano said additional security was on hand at school campuses Friday, a day after a 14-year-old was caught with a .25-caliber handgun and 50 rounds of ammunition.

The arrest occurred about 24 hours after rumors spread that someone had threatened on Facebook to open fire at the school, according to Superintendent Mike Berg.

Catalano said school was dismissed about noon with no incidents.

In Visalia, police arrested a 14-year-old Woodlake boy Thursday in connection with a threatened Friday shooting at Mt. Whitney High School.

Sgt. Paul Esquibel of the Visalia police Youth Services Unit said Friday morning that the threat was directed at rival gang members.

Mt. Whitney High Principal Jeff Hohne said Friday morning that the incident also began with a threatening message on Facebook.

Hohne said he got a telephone call about 9:45 p.m. Thursday from a teacher notifying him of a Facebook message threatening Mt. Whitney High.

A student had received the message and told the teacher, who then called Hohne.

Hohne said he called Visalia police, which started the investigation that resulted in the arrest of the Woodlake boy. The boy did not attend Mt. Whitney, Hohne said.

Esquibel said that after learning of the threat, officers identified the boy who made it and arrested him.

Hohne said Visalia police increased their presence on the Mt. Whitney campus on Friday.

In Clovis, police spokeswoman Calli Biaggi said that a truant student was arrested Thursday with some household chemicals that can be dangerous.

Officials determined that the materials were not related to an incident in August when employees working at Memorial Stadium on the Buchanan High School campus found several 2-liter soda bottle-type bombs that contained some type of explosive liquid.

In Reedley, officials went on alert after some students got a text message suggesting that an incident might happen at a campus rally Friday.

Reedley High Principal Rod Cisneros said four Reedley police officers were on campus, the rally went on as planned, and there were no incidents.