Shoulder to shoulder they stood: imams in kufis, ministers in robes, rabbis in skullcaps, elected officials and community leaders in business suits.

Against that backdrop at City Hall on Tuesday, Mayor Nutter condemned the "ignorant act" of the person who left a severed pig's head outside the Al Aqsa Islamic Society mosque and school in North Philadelphia. The head was found Monday morning.

Dropping part of a pig at a mosque has a special significance because pigs are anathema to Muslims who observe halal dietary laws.

"Someone tried to desecrate the mosque and its peaceful people. That, of course, will not be tolerated," said Nutter, who also announced a $2,000 reward for information leading to the conviction of "anyone engaged in a hate crime" in the city.

The reward, in a new category that was spurred by the Al Aqsa incident, is similar to existing rewards for homicides and the illegal possession of guns.

Police are reviewing surveillance video from the mosque and interviewing witnesses in an effort to identify the perpetrator or perpetrators.

Police Commissioner Charles H. Ramsey said his units are trying to enhance video to capture the tag number of the red pickup truck from which a person can be seen throwing something at the mosque around 10:55 p.m. Sunday.

Speaking in Arabic through an interpreter, Al Aqsa Imam Muhammad Shehata told reporters: "We all come for the same roots, the same mother and father, Adam and Eve. . . . The best among the believers are the ones who do not harm anyone with words or violence."

Marwan Kreidie, head of the city's Arab American Development Corp., a community development group, said those behind the incident "might have thought they were doing something against" the Islamic State.

"In fact," he said, "they are doing exactly what the radicals want them to do. They want America to appear to be anti-Muslim. This will help them in their recruiting; this will help them in their propaganda. We can't let the extremists win."

Mayor-elect Jim Kenney began his remarks with traditional greetings in Arabic and Hebrew.

"Each and every one of us Philadelphians and Americans should be outraged at what happened at Al Aqsa. Not that long ago in this country, three Catholic churches were burned to the ground in Philadelphia. One, St. Michael's, right close to Al Aqsa.

"This country exists for the opportunity for people to come here and to have a better life," Kenney continued. "Once they get here, we are going to protect them. We are not going to allow these folks who think they can intimidate people in our city to do this anymore. . . . We are here. We have your back. We're not going anywhere."