UPDATE 4:30 P.M.: We Energies tells WTMJ a contractor was on the ramp installing a gas main when a crack was discovered. They did dig 20 feet underneath the freeway to investigate.
They are working with the DOT and the Milwaukee County Sheriff's Office to investigate what caused it and to repair it.
Travel into Milwaukee's southwest side will be tough this afternoon due to a sink hole impacting part of the Hale Interchange.
The Milwaukee County Sheriff's Office says the sinkhole, measuring about 20 feet long and 8 inches deep, has closed the ramp that connects 43 northbound to 41/894 northbound.
The issue came up as We Energies was doing digging in the area.
While local and state road crews are at the scene, the repairs are expected to keep the ramp closed through the afternoon rush hour.
We will update this story as more information becomes available.
You can keep up to date with interactive traffic maps by clicking here.