Investigators were reviewing video footage and identified numerous suspects who could be charged with riot, attempted arson or other counts after a peaceful demonstration over the firing of Penn State football coach Joe Paterno turned unruly.
Crowds toppled a television news van and at least one photographer was pelted with a rock when thousands of people gathered in downtown State College late Wednesday, police said.
"The crowd initially was a peaceful demonstration against Coach Paterno's firing. The crowd quickly turned from a peaceful demonstration to a riotous mob," State College police said in a statement Thursday.
"The mob attempted to light vehicles on fire, and tore down light posts and street signs."
Some people threw rocks, bottles and hard objects at police and citizens, authorities said.
In the statement, police estimated the crowd totaled as many as 4,000 to 5,000 people and that officers made numerous orders to disperse, but eventually had to use pepper spray. About 100 police officers were downtown, many wearing helmets.
Authorities did not say how many arrests had been made.
Paterno had announced earlier Wednesday that he planned to retire after the season and expressed remorse for not having done more after he learned of sex-abuse allegations that had been lodged against a former longtime assistant coach. On Wednesday night, the board of trustees announced his immediate firing.
Meanwhile, a group that advocates for the rights of people abused by Catholic priests released a statement cautioning Paterno's supporters to think about the consequences of their actions.
"As for the students who are rallying around Paterno, we hope university officials will ask them to consider the anguish their actions are causing the victimized children as well as other members of their community who are victims of sexual violence," BishopAccountability.org said in the statement.
"To observers of the Catholic crisis, this phenomenon is sadly familiar," the group said."The students are similar to the parishioners who rally around abusive priests and complicit bishops. This kind of deference to powerful authority figures helps create a culture in which victims are silenced and officials feel entitled to hide crimes rather than calling the police."