What was going on with law enforcement cars tonight?

I was headed home at 12:30 am – 1 am and was on Fannin by OST before heading on 610 whenever I saw a procession of like 20-30 cop cars (SUV + truck) all with their lights on with no siren all headed down the same road going the speed limit. I think I might've seen one non-cop car in that procession with flashing yellow lights but it was hard to tell in a sea of red and blue. They even blocked incoming traffic to let all the cars pass.

Any thoughts on what might've happened? I checked the news when I got back home but didn't seem to find anything so I thought I'd throw the question here.