UPDATE : GREENWICH, Conn. — The lockdown is over Wednesday afternoon at Greenwich High School, the police department announced via Twitter.
Here is the full text of the Tweet [typos fixed], which was sent at about 4 p.m.:
"GHS LockDown is over. No injuries. GPD investigation cont. Dismissal will be followed per BOE transportation plan. Thank You for your cooperation."
The school had been on lockdown since midday and dismissal had been delayed after an unspecified threat, police said.
original story: GREENWICH, Conn. -- Greenwich Police are continuing to investigate a threat at Greenwich High School that led to the school being placed on lockdown. Dismissal has been postponed and students are being held while police investigate.
School officials said that police are not releasing details yet in order to ensure the safety of students and staff, and to ensure the integrity of the lockdown operation.
"We understand you are concerned about the time of release, please know that it takes time to move through a school of this size," school officials said in a 3:30 p.m. message to parents. "Dismissal will not take place until the police deem the site is safe for all. We will update you with more information as soon as we are able to."
No other schools are involved and numerous police are on the scene, police said. Nobody has been injured and everyone is safe, police said. Police said that it was not a bomb threat.
The school was supposed to dismiss at its normal 2:15 p.m. time. All other schools are conducting regular dismissal.
Tyler Phillips was one of the motorists parked outside the school waiting for students to be dismissed. He was waiting to pick up a friend's sister.
He's heard that students have been gathered together as police check bags and go through classrooms. He said he's heard from others in the lineup that the wait for the students to be dismissed could be anywhere from two to four hours.
"They said they are putting everyone in the auditorium," he said.
The recent GHS graduate said he had experienced a lockdown before in 2013 at the school.
"GHS is a great school and they follow lockdown procedures very well. I'm sure everyone inside is safe," he said. "I am kind of concerned for my friends because they have never experienced something like this but I am sure it will work out."