The discovery of pipe bombs targeting prominent Democratic politicians and CNN is raising the threat of election-season violence largely unknown in the U.S. — and prompting uncomfortable questions about the consequences of leaders’ increasingly vitriolic rhetoric.

Police and witnesses say a motorist drove onto a busy bicycle path near the World Trade Center memorial in Manhattan and struck several people, then emerged from the vehicle screaming and brandishing imitation firearms.

The city of New York is largely considered the top terror target in America and an explosion in the city’s Chelsea neighborhood Saturday evening immediately set off fears another attack.