Some of the teens who beat a man near Independence Hall July 29 during an afternoon attack have been identified as Mastery Charter students, a school official said Monday.

Surveillance footage taken of the attack, which occurred around 2 p.m. -- hours before the Friday night teen mob violence in Center City, shows six male teens, some carrying back packs, walking north on Fourth Street, just below Walnut, when they come upon a man walking south.

The man, who police said is 36, gives the teens room to pass on the sidewalk when one of the teens, who is without a shirt, suddenly punches him in the head. Two others then join in, punching and kicking the man.

An eyewitness yelled out and the students fled. The victim was treated at a hospital for jaw injuries.

Four of the suspects have been identified as 8th and 9th graders at Mastery's Lenfest campus, which is located on Chestnut Street, a few blocks from the attack, said Mastery CEO, Scott Gordon.

In the days after the incident, school officials went door to door in Society Hill, requesting security camera footage, Gordon said.

The school has notified police of the students identities, Gordon said. The two other students in the video are also believed to be Mastery students, Gordon said, but have yet to be positively identified.

The students had completed their final summer school session about an hour and half before the attack and had been hanging out downtown, he said.

Police said they have additional - and better quality security footage that will help them make arrests.

None of the teens have been charged yet, but police expect arrests as early as Tuesday, said Lt. Ray Evers, a Police Department spokesman.

Mastery has won high praise in recent years for its ability to turn around once-troubled middle schools. In July 2010, President Obama singled out Mastery for dramatically boosting test scores and curbing school violence.

Oprah Winfrey gave Mastery a $1 million grant as part of her Angel Network program last year.

Mastery educational approach aims to prepare students for college with a strict behavior code. Over 90 percent of Lenfest students go onto college, Gordon said.

"We are horrified and shocked that our students were involved in this," he said. "This behavior is completely unacceptable and will not be tolerated."

All of the students involved in the incident face expulsion, he said.

School officials on Monday sent a letter to neighborhood residents and businesses, apologizing.

"Mastery now has work to do to repair the damage these students have done to the trust we have built," the letter read.

"Random violence has become a phenomenon amongst some teens recently," it continued. "This incident is making us reflect on what more we need to do to counter this trend."

Contact staff writer Mike Newall at 215-854-2759 or mnewall@phillynews.com or Mike Newall on Twitter

Inquirer staff writer Martha Woodall contributed to this article.