After a band of 150 teenagers rampaged in Center City, police said today they would beef up patrols in the area and take a "hard line" against troublemakers.

"This is unacceptable, and I don't think they realize what they're doing to the image of the city," said Deputy Police Commissioner Kevin Bethel.

Yesterday afternoon, police arrested 16 teenagers who rampaged through Macy's department store on the 1300 block of Market Street and the surrounding streets.

The teenagers, who came from at least eight different schools throughout the city, congregated at the Gallery at Market East around 4:45 p.m., where they were turned away, police said.

The crowd left the Gallery and ended up at Macy's where they knocked over displays and caused about $700 worth of damage, police said.

City Councilmen James F. Kenney and Frank DiCicco watched the mayhem unfold from Kenney's second floor office yesterday, which faces down Market Street on City Hall's east side.

They saw throngs of teen-agers flowing up the stairs from the subway, pouring briefly into Macy's, then emerging from the department store, fists flying.

"It was nauseating and frightening and sad that one young person would actually stand over another person and kick them in the face," Kenney said.

He and DiCicco asked Mayor Nutter and Council President Anna C. Verna to sue social media sites if they were used to organize the fracas, but what they really want is to force some mechanism for detecting similar organized threats and alerting the police.

"I think that the citizens of this city have the right to shop, work, use public tranportation and not be pummeled to the ground," Kenney said. "This is urban terrorism. If they're using those sites to conduct this thuggery, than I want to find out if it's true, and I want the get the appropriate legal action to get them to warn us."

What compounds the outrage of the incident, Kenney said, is that many businesses have been kicked not just by the economy, but by the recent snow storms, and now must contend with "this."

It was unclear this afternoon if yesterday's rampage was spontaneous or organized through social media sites.

Police have pointed fingers at social networking sites for playing roles in two previous incidents.

On December 18, gangs of youths - some numbering up to 100 - gathered at the Gallery and then marauded through Center City. The teens assaulted some holiday shoppers including a Center City attorney and a doctor. Police at the time said the incident had been organized on Facebook.

On May 30, as many as 10,000 youths swarmed South Street, catching police off-guard and overwhelming officers. A cabdriver was carjacked and two other people were pulled from their cars and assaulted. Investigators said the event appeared to have been organized via social networking sites.

Yesterday, the crowd frightened Center City workers who crossed paths with them.

"I was walking through Macy's to the train at about 5:20ish when mobs of kids began swarming the store," said Sandy Astrono, 39, who works in offices housed above Macy's.

"I ran to the shoe department thinking someone had a gun," Astrono said. "Security guards were running and some of the kids had their shirts off and were fighting."

Afterward, the teens took to the streets, throwing snowballs, starting fights with each other and knocking over pedestrians.

Sixteen teenagers - ranging in age between 14 and 17 - were charged as juveniles with disorderly conduct and rioting. One girl was charged with assault, police said.

"We're going to take a hard line," Bethel said this morning in describing what the police would do to deter a repeat.

Courtney Poaches, 20, an employee at Payless Shoes in the Gallery, said violence has become routine at the mall and security could do little to prevent it.

"This is getting out of control. It's everyday, every single day," Poaches said. "They outnumber our guards."

Staff writer Elisa Lala contributed to this article.