Students at two San Fernando Valley high schools who in separate incidents allegedly threatened to shoot their classmates were arrested in recent weeks, authorities said Monday, resulting in searches of homes that turned up multiple weapons and dozens of rounds of ammunition.

Investigators with the Los Angeles School Police Department said they found five guns in total in the two homes they searched. In each, the weapons and ammunition were stored in unsafe locations.

“Our school police officers and detectives will continue to aggressively investigate all school safety threats and follow up at the residence of students or other locations where we believe access to firearms are present.” – Chief Zipperman @CityAttorneyLA #Teamwork #LockItUp pic.twitter.com/4qfEvFcoZl — LA School Police (@LASchoolPolice) March 12, 2018

The discoveries led the Los Angeles City Attorney’s Office to charge two of the students’ fathers over the unlocked guns.

Two of the teenagers were arrested in February for making threats against Granada Hills Charter High School and Chatsworth Charter High School students, according to City Attorney Mike Feuer.

A third teenager was arrested on March 6 for another threat against Granada Hills Charter students, according to LASP Sgt. Nestor Gonzalez.

The arrests of the students in February came days after 17 people were killed in a shooting at a Parkland, Florida high school. Following the massacre, law enforcement agencies across the region saw a spike in reports of threats amid a wave of greater public concern over gun violence in schools.

#news: "we prosecute parents when they don't lock up their #guns which end up in their kids' hands. #gunviolence pic.twitter.com/GJfLZRScxw — LA City Attorney (@CityAttorneyLA) March 12, 2018

Since the Parkland shooting on Feb. 14, LASP has received notification of hundreds of threats, according to Officer Sandy Romero — 235 criminal threat calls in all with 21 arrests across schools within the Los Angeles Unified School District boundaries as of Feb. 28.

The threats included those made to other students and against entire schools, said school police Sgt. Julie Spry. She could not say immediately which schools those students attended.

RELATED STORY: Here’s a timeline of Southern California school threats that have been reported after the Florida shooting

Feuer on Monday said the charges against the parents of two of the Valley students were part of a city effort to keep guns out of the hands of people who should not have access to weapons.

“Lock up your guns — it’s the law, there’s no excuse not to, and it could make the different between life and death in the community in which you live,” Feuer said. “Store your guns safely.”

According to LASP Detective Joseph Camello, all of the guns were legal to purchase in California. But a new city law targeting unsecured handguns in homes criminalized the unsafe storage of weapons.

In the Chatsworth incident, LASP officers went to the home of a 16-year-old student after learning of an alleged Feb. 5 threat to shoot up the school. The teen had previously referred to his parents’ guns, officials said.

When police searched the home on Feb. 17, they found four guns and 90 rounds of ammunition. The city attorney’s office said the officer found three handguns in a bag behind a dresser in the master bedroom. There was also a rifle in the closet.

The guns were registered to the father of the student, 59-year-old Robert Christy, according to Camello. Christy was charged with three counts of unlawful storage of a firearm, Feuer said.

The guns included a .40-caliber Smith & Wesson M&P semi-automatic handgun, a .38-caliber snub-nose revolver, and another revolver Camello described as “antique.” All the guns were legal to purchase in California.

If convicted as charged, he faces up to 18 months in jail and a $1,000 fine for each charge.

In the first Granada Hills incident on Feb. 27, police arrested a 17-year-old student who allegedly made threats against the school, which included an Instagram post.

Gonzalez said officers found out rumors were circulating around the school that the student might be in possession of a weapon or have access to one. When they searched the student’s home, they found a loaded semi-automatic handgun unsecured in a bag in a closet, officials said.

They also found a magazine with seven rounds of ammunition in the holster containing the firearm.

The father of the student, Dazo Esguerra, 50, was charged with two counts, including criminal storage of a firearm and unlawful storage of a firearm. He faces up to 12 months in jail, as well as the $1,000 fines for each charge.

In the second Granada Hills incident reported on March 6, school police officers investigated the alleged threat written on a napkin that said the student was going to kill everyone at the school, according to Gonzalez.

“He thought it was a joke; we still arrested him,” Gonzalez said. “No weapons were recovered.”

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Brian Bauer, the executive director of Granada Hills Charter High School, said in an email to parents over the weekend that “some students” were arrested by the school police department. In some of these cases, he wrote, students possessed knives and drugs on campus.

He said the police investigations were the result of student and parent tips.

“We feel fortunate that our school community, parents, students and staff not only feel comfortable about bringing information forward, they know it’s a responsibility,” Bauer told the Daily News. “(They know) that we will act on it as a school — that we take information like that…very seriously.”

Bauer’s email said the school did “not have evidence, nor do we believe, that any of the students brought a firearm into campus.” Camello also said none of the weapons found in February were brought to school.

Bauer asked parents and guardians to continue to review and monitor their child’s social media accounts and to turn over any concerns to the dean’s office or an administrator.

Granada Hills Charter High, an independent public charter school, contracts with LASP for a full-time police officer on campus. The school has had excellent officers who are “fully integrated here at school,” Bauer said.

RELATED STORY: LA City Council passes tough handgun storage law

Bauer said he was recommending two students for expulsion for disciplinary infractions, but noted those cases were not related to weapons or drugs.

Separately, Camello noted there is also an ongoing case involving a student at Birmingham Community Charter High School in Lake Balboa, who is believed to have posted something on social media that involved him holding what appeared to be a rifle. It included the hashtag #schoolshooter, he said.

The post did not rise the level of a criminal threat because of its unspecific nature, Camello said. However, officers followed up at the juvenile’s residence, conducted a search with the parent’s permission and seized a rifle there that was not stored appropriately.

The parent involved had prior offenses and the case has been forwarded to the Los Angeles County District Attorney’s office, he said.

Editor’s note: This article was updated from an earlier version to note that Birmingham Community Charter High School is located in Lake Balboa.