State Police have ticketed at least four drivers today for driving expensive vehicles at excessive speeds in greater Boston, part of a crackdown on participants in the Gumball 3000, an international road rally.

Troopers were posted on Interstate 93 in Medford this morning, expecting to intercept drivers as they head north to Canada for the next leg in the 3,000-mile international road trip, according to State Police and the road rally’s website, gumball3000.com.

State Police spokesman David Procopio said drivers have made 911 calls after seeing the vehicles zip past them at a high speed. Four drivers were stopped for speeding in Medford this morning, he said. None of the drivers were from Massachusetts.

“They are from different parts of the world,” Procopio said. “One was from Dubai and another, California.”

Procopio said rally participants are heading north to Toronto so troopers are watching northbound highways.