Closure on I-45?

Driving north on I-45 and the highway was closed right before exit 34 with no advance notice. Three motorcycle cops had the road closed and many cars were stuck on the highway because there was no opportunity to get off the highway before the road closure. Many cars, including ours, drove against traffic to get off the highway. The highway opened up again around exit 36. I didn’t see any ambulance, fire truck, or road workers in the closed area. I did see a few more police vehicles and a few white work trucks with no signage. No one was outside their vehicle as far as I could tell. Any idea what’s going on?