LITTLETON, Colorado – Latest news on Columbine High School and other schools in the Denver area (local time):

10:35

Investigators said that a woman who had made undisclosed threats to security at Columbine High School had bought a shotgun and ammunition shortly after landing in Miami from Denver.

Dean Phillips, the FBI's special agent in Denver, said that a "massive human hunt" was underway for 18-year-old Sol Pais. She went to Colorado on Monday night and was last seen in the foothills west of Denver.

Phillips claims that Pais did not threaten Columbine, but the investigators were worried as she had expressed her enthusiasm for the 1999 shooting.

Doors were locked in Columbine and at more than 20 other schools in the Denver area on Tuesday afternoon after the threat.

The lockouts come just days before the 20th anniversary of a shooting in Columbine that killed 12 students and a teacher.

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18h

FBI officials in Colorado said the woman who made undisclosed threats against Columbine High School was "infatuated" with the 1999 shooting and was considered armed and dangerous.

The Rocky Mountain Safe Streets working group of the FBI issued a notice Tuesday for the police looking for Sol Pais, 18 years old. She says that she has been trying to buy firearms and that the police who come in contact with her should detain her and assess her mental health.

The Jefferson County Sheriff's Office and the FBI announced that Paul Pais had gone to Colorado on Monday night and that he had been last seen in the hills to the west of Denver. We do not know where she comes from.

Threats led school officials to close the gates of Columbine and about twenty other schools in the Denver area before releasing the students for the day.

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4:50 p.m.

Colorado Governor Jared Polis said the threat to lock up Columbine High School and other schools in the Denver area involved an armed person who "may want to harm our schools or our schools." children. "

Polis said Tuesday that Colorado's Ministry of Public Security was working with the FBI to protect public safety.

He said that he had no other information.

The Ministry of Public Security has urged schools to urge schools to strengthen security and more than 20 of them have set up containment facilities.

The closing of the premises comes just days before the 20th anniversary of a mass shootout at Columbine High School that killed 12 students and a teacher. Authorities say they are looking for a woman suspected of threats. They say that she should be considered armed and extremely dangerous.

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4:10 p.m.

All schools in the Denver area are being urged to step up security after what appears to be a credible threat has resulted in a lockout at Columbine High School and at over 20 other schools in the area.

Patricia Billinger, a spokeswoman for the Colorado Department of Public Safety, said the agency made the recommendation because Tuesday's threat was deemed "credible and general".

At least one school district has considered this advice. The Aurora public schools tweeted that the students were released in a "controlled" way and that additional security measures were put in place throughout the district as a precautionary measure.

The lockouts come just days before the 20th anniversary of a mass shootout at Columbine High School, which killed 12 students and a teacher. Authorities say they are looking for a woman suspected of threats. They say that she should be considered armed and extremely dangerous.

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3:45 p.m.

As a result of a confinement at Columbine High School and in other schools in the Denver area, authorities claim to be looking for a woman suspected of threats.

The Jefferson County Sheriff's Office and the FBI announced that Sol Pais, 18, had gone to Colorado on Monday night and made threats, but he provided no details to this subject. They say that she was last seen in the foothills to the west of Denver, where are some of the locked schools.

They did not say where she came from.

Authorities have indicated that Pais is armed and considered extremely dangerous and that one should not be approached.

The doors were locked in Columbine and in at least 20 other schools in the Denver area, while the sheriff's office had declared that he was investigating a possible threat to schools related to an FBI investigation.

The students were sent back on time but after the school activities were canceled in Columbine.

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2:55 p.m.

Students leave classes after strengthening security at Columbine High School and more than 20 other high schools in the Denver area after a lockout caused by a potential threat.

Students carrying backpacks crossed the main gate in Columbine Tuesday afternoon, shortly after school officials announced that students from all locked schools were safe and would be sent back to their normal hours. . Students walked to pedestrian crossings and buses parked near the entrance.

Officials said post-school activities would take place in all schools, except Columbine, without explaining why.

A spokesman for the Jefferson County Sheriff's Office Mike Taplin said the locks implied an FBI investigation, but he could not provide any details. The sheriff's office previously said the locks were motivated by an investigation into what appeared to be a credible threat that could involve schools.

The closing of the premises comes just days before the 20th anniversary of a school shooting that killed 12 students and a teacher.

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2:30 pm in the afternoon.

Authorities say the enhanced security at Columbine High School and a dozen other schools in the Denver area is linked to an FBI investigation.

A spokesman for the Jefferson County Sheriff's Office, Mike Taplin, said Tuesday's school lockdown implied an investigation by the FBI but that he could not provide any details. The sheriff's office has previously stated that the locks were motivated by his investigation into what appears to be a credible threat that may involve schools.

A message left to an FBI spokesperson was not immediately returned.

School officials said the doors were locked but classes were continuing at Columbine and two other schools nearby and at other schools further away from the same district.

The closing of the premises comes just days before the 20th anniversary of a school shooting that killed 12 students and a teacher. There was no immediate indication if there was a connection with the birthday.

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1:40 p.m.

Columbine High School and about a dozen other schools are locked out, law enforcement officials say they are investigating what appears to be a credible threat that may involve schools.

School officials said the doors were locked, but classes were continuing Tuesday in Columbine and two other schools nearby and in other schools further away from the district.

The Jefferson County Sheriff's Office stated that deputy ministers were stationed in the affected schools.

This closure comes just days before the 20th anniversary of a shootout at the school that killed 12 students and a teacher. There was no immediate indication if Tuesday's lockdown was related to the anniversary.