Teen girl accused of plotting school shooting released from hospital, charged Authorities said no one else knew of the alleged plot.

 -- A Maryland teenage girl accused of plotting a shooting at her high school was released from the hospital this morning and taken into custody, where she was served with outstanding arrest warrants, officials said.

Nicole Cevario, 18, had been in the hospital since March 23, after her father told officials at Catoctin High School in Thurmont, Maryland, about a "potential threat of violence toward the school," the Frederick County Sheriff's Office said.

Authorities searched Cevario's home, where they say they found a diary that indicated she planned to carry out a mass shooting at her high school less than two weeks later, on April 5. Her diary mentioned the 1999 Columbine High School shooting in Littleton, Colorado, and the 2012 Newtown, Connecticut, elementary school shooting, Frederick County Sheriff Charles Jenkins told ABC News.

The sheriff's office said Cevario's journal showed she had been plotting the alleged attack "for some time and had been compiling intelligence on behavior activities of the school, noting emergency procedures associated with drills conducted by school staff and obtaining intelligence on the school resource deputy."

Authorities searching Cevario's home also found a shotgun with ammunition and "bombmaking materials to include pipes with end caps, shrapnel, fireworks, magnesium tape and fuse material," the sheriff's office said.

The sheriff's office said earlier that Cevario was struggling with mental health issues.

After Cevario was released from the hospital today, she was taken to the Frederick County Adult Detention Center, where she is being held on no bond pending an evaluation from the Maryland Department of Health and Mental Hygiene, the sheriff’s office said.

The arrest warrants were for possession of explosive material with intent to create a destructive device and possession of incendiary material with the intent to create a destructive device, the sheriff’s office said previously.

Frederick County Sheriff Charles Jenkins said all the items Cevario bought were legal. Authorities also said that no one other than Cevario was involved.

The office of Cevario's attorney declined to comment.

Jenkins said earlier this week, "I have no doubt based on what we saw in her diary, the evidence we found, the information that we have taken throughout the investigation, that this was going to occur ... April 5."

There was never a weapon or explosive device on school property, authorities said, and the materials were never combined into an explosive device, officials said.

Jenkins added of the suspect's parents, "I can't tell you how thankful I am that they stepped forward, offered this information to school administrators and contacted us. Without their help with this thing, we would have been dealing with an aftermath, rather than averting."

ABC News' Dennis Powell contributed to this report.