“I know a lot about Pennsylvania, and it's great,” Trump told supporters gathered in Pittsburgh's David L. Lawrence Convention Center. “How's Joe Paterno? We're going to bring that back, right? … How about that whole deal?”

Paterno died in January 2012, just months after being fired from his position as head coach of Penn State's football team amid a child sex abuse scandal involving former defensive coordinator Jerry Sandusky.

A spokesman for Trump later told David Martosko, U.S. political editor for The Daily Mail, that the GOP front-runner was referring to efforts to bring back a Paterno statue taken down after the Sandusky scandal.

During his speech, Trump also spoke about Pittsburgh's manufacturing industry, immigration, the trade deficit with China and Pittsburgh Steelers quarterback Ben Roethlisberger, who he called a great friend, WPXI reported.

Outside the convention center, protesters and supporters clashed. Chants of "USA!" and "Build that wall!" filled the air, along with shouted profanity. Police in riot gear separated the opposing sides.

Pittsburgh police Chief Cameron McLay told WPXI officers made a handful of arrests after several protesters pepper-sprayed officers and Trump supporters. No serious injuries were reported.