A town-hall meeting to discuss controversies surrounding police stop-and-frisk practices in Philadelphia roiled with anger and shouting from the audience Friday night at a North Philadelphia church.

Mayor Kenney endured a slew of insults - he was called a "liar" and "pig politician" - as he tried to explain how his administration was making sure every police stop of a pedestrian abided by the U.S. Constitution.

Chris Norris, one of the forum moderators at New Vision United Methodist Church, asked the mayor whether he was willing to apologize to people who have been illegally stopped by police.

The audience grumbled as Kenney questioned how stop-and-frisk was defined, trying to put a fine point on a subject fraught at that moment with emotion.

The mayor eventually said that to the extent illegal stops have occurred since he took office, "I do apologize for that."

He said it was important that the police no longer use pedestrian stops "as a fishing expedition."

During his campaign last spring, Kenney vowed that if he was elected, "stop-and-frisk will end in Philadelphia, no question."

After taking office, he offered a more nuanced position, explaining that pedestrian stops must continue, but that they need to be constitutional.

In March, the Pennsylvania ACLU reported that of 200,000 pedestrian stops in the first half of 2015, 33 percent were made without reasonable suspicion that a crime had occurred.

Blacks accounted for nearly 70 percent of stops, according to the ACLU report.

The ACLU sued the city over stop-and-frisk in 2010, and that led to a settlement with the city that included monitoring by the ACLU with regular public reports.

Kenney and Police Commissioner Richard Ross told the audience that new measures were in place to require more detailed reporting by officers after each pedestrian encounter, followed by more monitoring by supervisors, as well as training and discipline if necessary.

For much of the meeting, Kenney and Ross were targeted by certain audience members with verbal abuse and personal insults.

The ACLU deputy legal director, Mary Catherine Roper, also was mocked.

Clergy members repeatedly tried to bring order, and at one point had brief success. But finally, the Rev. Gregory Holston, senior pastor at the church, said the audience behavior was too much and abruptly halted the gathering.

SEPTA Transit Police Chief Thomas J. Nestel III, who was live-tweeting the event, said the emotion in the room was intense.

"The need for change is in the air," he wrote.