Parents, authorities, and facilities are on edge after over a dozen schools between Texas and California received similar threats of alleged active shooters, forcing lockdowns to go into effect on Tuesday.
Sources tell ABC13 that the same phone number called dispatchers in Texas and reported false claims of active school shooters and alleging there to be victims.
In addition to Houston and Waco, ABC13 sources said false reports were also made in Pflugerville and a fourth Texas school district.
In Houston, Texas, law enforcement said they responded to a reported active shooter at 1 p.m. at Heights High School.
Initially, the caller told police there were 10 victims at the high school, according to investigators.
For safety precautions, Hogg Middle School, Harvard and Travis Elementary School were also issued to go into lockdown, according to Houston ISD.
In a statement at Tuesday's Commissioner's Court, Harris County Judge Lina Hidalgo said two students got into a fight, and there was never a threat of an active shooter, and there were no injuries.
"The security of our students and staff is our top priority," Houston ISD said in a tweet.
Houston Mayor Sylvester Turner released the following statement:
"I want to thank Houston Police, Houston Fire, the Harris County Precinct One Constable's Office, and Houston ISD for their prompt response at Heights High School. While the reports of an active shooter turned out to be false, we are reminded that student safety and school security are paramount on the minds of students, parents and employees of all school districts. Today's response to the emergency calls reinforces how seriously our first responders take these incidents and illustrates the constant training they undergo to take such quick and responsive action."
It was unclear if anyone had been taken into custody.
In Waco, Texas, authorities responded to a similar report of an active shooter also at about 1 p.m. at Waco High School.
Lake Air Montessori Magnet School, Hillcrest, and Crestview Elementary School were also under lockdown as a precautionary measure, according to Waco ISD.
"Officers and surrounding agencies have cleared Waco High School, and we have confirmed there is no active shooter," Waco police said at 3:40 p.m.
ABC affiliate KXXV reported there was a "large police presence" at the high school.
Waco ISD and police touted their readiness and fast-acting response to the alleged threat.
"This is one of the reasons why we do these trainings. Thankfully this time it was not a (real) threat," Waco police said.
"We saw on social media that there are other cities in this state that are also dealing with this incident," Waco police said.
When asked if these false reports are somehow connected, investigators said they "are not sure."
There were no reported injuries.
In Pflugerville, Texas, a station in Connally High School
In Hollywood, California, Hollywood High School went into lockdown after a caller told police six victims allegedly were shot.
However, after a full lockdown of the campus and a massive search, investigators said no shooting victims were found.
"Recent reports of a critical incident at Hollywood high school are unfounded and, after swift law enforcement response and internal individual classroom verification, we are deeming the incident as a hoax," said the Los Angeles Unified School District in a tweet.
All students are safe and accounted for, according to Los Angeles Unified School District. Classes resumed at about 11 a.m.
WATCH: Active shooter report at Hollywood High School deemed a 'hoax,' authorities say
In Madera, California, police said a caller told dispatchers that there were three armed people at Nishimoto Elementary School at about 9:30 a.m., forcing the school to go into lockdown.
Jack G. Desmond Middle School and Matilda High School were also put into lockdown due to the alleged threat.
Madera police said they always take these calls seriously and are investigating who made the fake 911 call.