Police have arrested a suspect and are still searching for the gun allegedly used in an incident that prompted the lockdown of Community College of Philadelphia and the nearby Masterman School this morning.

Students who were asked to remain inside Community College of Philadelphia (CCP) were being released by 12:30 p.m. as Philadelphia Police lifted the secure perimeter around the school on Spring Garden, but continued to search the school's buildings.

Related link: Philly universities vigilant after threat of shooting

CCP student Andrew Sopko claimed he was walking down a hallway in the school's Winnet Student Life Building when he noticed a commotion -- and saw the suspect rush past him holding a black handgun.

"It was the craziest, surrealest thing I've ever seen in my life," said Sopko, 24, of East Falls, who did not know the suspect personally.

Sopko described a "stampede" as the 20 or so students in the hall fled from the building. He said he had no idea if he was witnessing an active shooter or a small one-on-one confrontation, as police have described the incident.

Related link: Gunman opens fire at Oregon college in mass killing

"When you have a lot of people in a small area, and a guy with a gun -- who knows?" Sopko said. "Especially with everything that's been going on, it was too hard to tell."

He described the gun as a black, boxy Glock-like weapon.

CCP student Angela Saltzer, 21, of Northeast Philly, said she was in math class when she got a phone call that a man with a gun had been reported.

"It really scared me, it scared me really bad," Saltzer said. Her professor asked her and her fellow students to remain in the classroom with the lights off, which had begun at 9:45 a.m., until they were cleared to leave by police around 12:45 p.m.

"I was really scared, with the community college in Oregon getting shot up... since there was a threat out yesterday," she said. "I'm just glad to be out and be safe."

Details on the suspect are pending, but police commissioner Charles Ramsey described him as a black male, about 5'4", wearing grey pants, a blue shirt and a red hoodie.

The suspect got into an argument with another individual, who may have been a former student, on the street near the school, Ramsey said. The gunman then went into the Winnet Building after brandishing the gun.

No shots were fired but students were ordered to stay in their classrooms as police searched school buildings. 

"These are two individuals that have a history," Ramsey said.

The lockdown came as universities in the Philadelphia area remained on edge after the FBI and ATF warned that someone had posted an online threat against an unspecified local school last week warning of an impending threat.

That warning stated that an attack was to be made at a university at 2 p.m. Monday.

That posting appeared to have been made on the website 4chan's Robot9001 or r9k forum.

Authorities were investigating whether Chris Harper-Mercer, the suspect in a shooting at an Oregon Community College that killed nine, also posted a warning on the r9k message board a day before his attack. 

Police said on Tuesday that there was no connection between Tuesday's lockdown at the Community College of Philadelphia and the online threat. 

"This doesn't look like it has anything to do with yesterday at all, anything to do with Oregon, anything to do with any of that," Ramsey said.

Chief Joe Sullivan of the counterterrorism unit said that officers working with CCP police would search every school building, top to bottom, so that the school could open again Wednesday without any further cause for concern.

He praised his officers' performance as the lockdown ended and said they were prepared for this type of incident regardless of the recent shooting or other threats.

"We live on edge. We don't go on edge," Sullivan said.