Bomb sniffing dogs are led away from Fountain Valley High School after members of the Orange County Sheriffs and Fountain Valley Police conduct a bomb sweep of the campus on Wednesday. (KEVIN CHANG, HB Independent / September 4, 2014)

Police locked down two Fountain Valley high schools Wednesday morning after school administrators received an email from a student's account stating that he had planted explosives on one of the campuses.

The email, which was sent around 10 p.m. Tuesday from a 17-year-old Fountain Valley High School student's account, went on to say that the boy would come onto the campus with an assault rifle to kill any survivors, said Sgt. Tony Luce.

School administrators received the email just after 6 a.m. Wednesday and immediately canceled classes and called police, Luce said.

Authorities evacuated teachers and administrators from Fountain Valley High School, at 17816 Bushard St., and the neighboring continuation school Valley Vista High, at 9600 Dolphin Ave.

When police questioned the student at his home, the boy gave police access to his cell phone, computer and email account. Officials suspect that the teenager's email account was hacked.

"He's denying sending the email," Luce said. "There's no evidence that it was sent by him."

The student, who has not been identified by police, does not appear to have access to any weapons, authorities said.

Still, authorities used police dogs and the Orange County Sheriff's Department's bomb squad to search the two high schools.

They did not find any explosive devices during their search, Luce said.

The bomb squad is taking school administrators and teachers back through their offices for a final check as a precautionary measure.

Police expect the schools to reopen in the next several hours. However, classes will remain canceled for the rest of Wednesday.

Authorities blocked the area of Bushard Street that runs from Talbert Avenue to Slater Avenue and are unsure when it will reopen.

Senior Sean Strayer, 17, was on his way to his first class at Fountain Valley High just before 7 a.m. when he learned of the threat through Twitter.

A fellow student had tweeted a photo of a police car on campus.

"I decided to go to school anyway," Strayer said. "I didn't know how big of a deal it was going to be."

This isn't the first time the high school has been locked down because of a threat. Someone had threatened to bring a gun to campus two years ago, which prompted officials to lock down the school, Stayer said.

"It's sad that we have to worry about these things, but we do," he said. "It's pretty scary."

Officials at the Huntington Beach Union High School District declined to comment about the threat.