Thousands of frightened Sheridan College students huddled in their classrooms yesterday as heavily armed police searched for a gunman.

The school was in lockdown for three hours. No gunman was found.

The sighting is now believed to have been a false alarm, but the incident shows how seriously officials take reports of gunmen in the wake of fatal and tragic campus shootings at Virginia Tech and Montreal's Dawson College.

The incident occurred the same day as the killing of three female students on a Louisiana university campus.

Sheridan's students were ordered to remain in their classrooms when a teacher and several students claimed to have seen a man, wearing a camouflage jacket, walking near the library hall and carrying what looked like a rifle or shotgun.

The man was wearing a camouflage jacket. It now appears he was carrying a piece of camera equipment, although police said they will continue their investigation. The three-hour lockdown began at about 2:15 p.m.

There's a possibility it could have been a tripod, said Inspector Jackie Gordon.

Sheridan president Dr. Robert Turner also said the witnesses were not sure they saw a gun. "I think this is a false alarm. That's our hope and our expectation."

Police are still looking for a man described as 6-foot, medium build, brown hair with a prominent bald spot and long side burns. He wore blue jeans, a green lumber-style jacket and thin glasses. Anyone with information is asked to call 905-825-4777, ext. 2215 or Crime Stoppers at 1-800-222-8477.

Tactical teams from Halton, Hamilton and Peel police descended on the campus. One man matching the description was taken into police custody, but later released. On any given day the campus could have 9,000 students and up to 1,300 staff members.

Allison Summers, 22, of Hamilton, was in her art history class with about 30 other students in B wing where the library is. After the announcement, they barricaded the door with chairs and garbage cans because the door does not lock. They went on the Internet to read media websites to find out why the school was locked down.

She said at about 3:15 p.m. the police burst into the room. "They came in with their guns and everything. They told us all to get down on the floor and asked if there was anyone who did not belong here."

Michelle Campbell, at her home in Waterdown, got word about a problem at the college after receiving a call from her husband Robert who was in Georgia on business. Her daughter Meaghan, hiding under a desk in a classroom, had tried to call home but in her anxiety hung up before her mother could reach the phone. She tried her dad's cell and got him right away. He phoned home.

Meaghan also sent a text message via her phone to her sister-in-law in Waterdown, her fiance Jay Ducarme at work in Milton and called her grandmother in Oakville. All scrambled to get to the college, fearing the worst.

Although Meaghan spent almost three hours under a desk, "the scariest part was leaving the room" after the OK was given. "Me and my girlfriends, we were all holding hands; some people were crying."

Samantha Gary, 20, was in her documentary class with about 10 other students. "We were all very anxious. It was pretty scary."