Deputies pulled a female passenger from the SUV as gas billowed out the door. Three police dogs, held back by deputies, barked loudly.
"Move away from the car! Roll! Roll!" a SWAT team member shouted to the driver with his gun trained on the man.
Authorities haven't said whether the suspects were armed or why they refused to come out of the SUV.
The standoff had begun at 4 a.m. when a Milwaukee County sheriff's deputy pulled up behind the SUV, which was stopped along westbound Interstate 94 near the city's major downtown interchange. The driver and passenger refused commands to come out of the vehicle.
More deputies and SWAT team officers converged near the vehicle -- and the waiting began. Dozens of drivers got stuck on the freeway as authorities shut down the road.
Mark Gauger got caught in the mess at about 5 a.m. as he was on his way to work in nearby Waukesha.
"For the life of me, I never expected to see something like that at 5 a.m.!" Gauger told the Milwaukee Journal Sentinel. "I was one of the fortunate few that were able to reverse down the exit ramp."
Several hours into the standoff, deputies directed backed-up vehicles off the freeway.