Officials at Boulder's Manhattan Middle School said they don't perceive a Dec. 3 threat found last month in a girls' bathroom as a "real safety concern." But there will be tightened security when students show up to class Monday — just in case.

Manhattan Principal Martha Gustafson sent an e-mail to parents Friday about the message found Nov. 7 that read: "We will all die December 3, 2007."

"We are convinced it is an act of vandalism only, and not a real safety concern," Gustafson wrote in the e-mail. "That being said, nothing is more important than school safety, so we will be operating under tightened security on Monday as well."

Gustafson said in the e-mail that she sent the note to families after receiving "a couple" of phone calls from concerned parents.

"I plan to bring my own children to school in the afternoon when they are finished with their elementary school on Monday," she wrote. "I am confident we will have a safe and fun day on Monday."

No one has been arrested in connection with the vandal-ism, but, Gustafson said, "We do have extremely strong leads."

Boulder police have a resource officer stationed at the 290 Manhattan Drive school on a regular basis. Officials wouldn't elaborate on what "tightened security" means.

Boulder Valley School District spokesman Briggs Gamblin said there will be "additional personnel" at the school, but he, too, declined to discuss security details.

"We are working with Boulder police," he said.

The school has determined the threat probably is unfounded based on a "threat assessment," Gamblin said.

"But you can't dismiss a threat when kids' safety is involved," he said.

Last year, a similar message was found scrawled in a Manhattan bathroom. Boulder police arrested a 12-year-old girl in that case.

Contact Camera Staff Writer Vanessa Miller at 303-473-1329 or millerv@dailycamera.com.