Clinton called the heated protests last night at the Republican front-runner's rally in Chicago "deeply disturbing."
"The ugly, divisive rhetoric we are hearing from Donald Trump and the encouragement of violence and aggression is wrong, and it's dangerous," Clinton told her supporters in St Louis, Missouri at a campaign rally.
"If you play with matches, you're going to start a fire you can't control. That's not leadership. That's political arson," Clinton alleged.
She was speaking to about 100 campaign volunteer, local media reported.