A man dressed in a black cape and wearing a gas mask approached the stage where Annie Lennox was performing at the University of Colorado Tuesday night and frightened her into retreating backstage, dailycamera.com reported.

CU Police Sgt. Gary Arai said the man, a 32-year-old Denver resident, was escorted out of the building by security around 9:30 p.m. and the concert resumed.

"A fellow who was dressed in a black cape, platform boots and a gas mask approached the stage," Arai said. "Lennox saw him coming and threw down her microphone and went backstage."

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He didn't know if charges would or could be filed, given that the man didn't climb up on stage with Lennox. Police are looking into the incident, dailycamera.com reported.

Lennox, in a Wednesday blog posting on her official Web site, described the incident as "really freakish and disturbing, whatever the hell it was."