UPDATE: April 7: The Los Angeles County Sheriff’s Department reported the arrest of Adrian Mendoza, the 18-year-old man accused of making a bomb threat to Walnut High School and Mt.Sac.

Mendoza, a student at both Walnut High School and Mt.Sac, was arrested on April 6 and was booked on suspicion of false report of as bomb or explosive device.

He was released on $20,000 bail late Wednesday night, according to a written statement from the Sheriff’s Walnut Station. He is scheduled to appear at the Pomona Courthouse April 8.

Mendoza’s motives have not yet been revealed.

On Thurs., March 24, traffic delays prevented the timely evacuation of Mt. SAC students and employees, after an emergency alert called for the immediate evacuation of the campus due to a bomb threat, which also threatened nearby Walnut High School and prompted the school to go on lockdown.

According to ABC7, Lt. John Saleeby of the Los Angeles County Sheriff’s office, the threat was phoned in to Walnut High School at around 10:24 a.m. Between 11:15 and 11:30 a.m. a phone calls and text messages were sent out to students through Mt. SAC’s emergency alert system telling students to leave campus due to the report of a threat.

The threat came from a picture that was circulating on social media. The picture featured a note that was allegedly found in the men’s restroom at Walnut High School and read: “There will be a bomb blown up today both here and Mt. SAC today at 2:45 p.m God be with you all.”

Despite the emergency alert and image circulating social media, many students were initially unaware of the threat, as they had not received the notification from the Mt. SAC safety alert system.

Upon learning of the threat, many students panicked as they tried to relay the situation to loved ones.

“When I first reached my car and was blocked in, I was shaking. I told my husband, mom, and roommate the situation — just in case,” said Mercedes Tseng, 24, communication major.

As students attempted to leave in their cars from campus parking lots, they were trapped in long lines of cars because of the increased volume of traffic and limited exits due to ongoing construction both on campus and on main streets near campus.

Due to the delays, it took some almost three hours to evacuate campus from the time the emergency alert was issued, despite California Highway Patrol and Mt. SAC public safety officers redirecting traffic in the area.

Students were both frustrated and scared as they attempted to comply with the notice for immediate evacuation.

“It was a pretty weak evacuation.” Walter Alvarado, 42, radiology major said. “It’s like trying to get out of a Dodgers game.”

Yesenia Carrasco, 25, child development major said the evacuation was “very, extremely messy.”

Military veteran Alfredo, 44, nursing major, expressed his frustration over the poorly planned, inefficient evacuation plan.

Alfredo also said, “it should have taken 45 minutes tops to evacuate the entire campus.”

Students who did not drive to school today waited at restaurants across from campus on Grand Avenue, or waited at the 7-Eleven across from campus.

At 12:12 p.m., Foothill Transit tweeted they would be sending extra buses to Mt. SAC to assist students needing a way to return home.

Walnut high school was placed on lockdown until 1:20 p.m., at which time officials concluded the campus was safe, and let out students.

At 3:12 p.m., the Mt. SAC emergency alert system sent out a text, informing students that the threat had been cleared and that classes would resume at 4:30 p.m.

Mt. SAC encourages students and employees who have not signed up for the emergency alerts to do so.

The source of the bomb threat is unknown at this time.