They're cracking down on rowdy teenagers looking to cause mayhem.
"They said there's a possibility of flash mobs tonight, so they're going to keep everybody out, said Andrea Guevara.
So Temple University student Andrea Guevara and her friends made new plans after being turned away from Love Park in Center City.
Philadelphia police officers lined the entrances of Love Park which was closed down for several hours Friday evening after law enforcement heard rumblings of a flash mob rumored to start there and move toward South Street.
"There were a number of youth who were in the area," said Lt. Pace of the 9th District. "No question about it, this was the area where they were going to congregate. We made sure we dispersed them."
Police have been out in force at critical times in recent weeks as the weather has improved, drawing more people outdoors.
Friday night, bike patrols circled Center City streets. Other officers were stationed at corners of concern like on 15th and Chestnut where there have been past problems, keeping foot traffic moving and loitering to a minimum.
It was just Thursday night when Action News reporter Dann Cuellar captured video on his iPhone at the H and M nearby.
Around a half dozen teens brawled inside the clothing store; one has already been arrested and police hope to identify the others.
Authorities say the precautions on a warm Friday night are all in the name of keeping people and property safe.
"We're very vigilant as a department to act on any information that we think is credible. Our primary objective is to keep people are safe," said Lt. Pace.
