'Transformers 4' filming in South Loop

Lots of action-movie fans are catching glimpses of “Transformers: Age of Extinction,” which is filming in the South Loop today and into the night.

The Chicago shooting makes for some neat still images and surely a fun diversion if the film happens to be bad when it’s released next summer. Fans have already been treated to explosions at the McCormick Place plaza (itself a building in disguise, made to look like Hong Kong) and low-flying helicopters over the Chicago River.

You might also be lucky enough to spot stars like Kelsey Grammer and Mark Wahlberg, who has been seen around the city and even had dinner with Mayor Rahm Emanuel two weeks ago. No word on whether Wahlberg’s staying with his man crush while he’s in town, but he did get to hoop it up this week with Jimmy Butler of the Bulls: