Milwaukee County Sheriff's Department and Milwaukee Police Department were investigating multiple incidents Wednesday morning. 

Here is what CBS 58 knows:

UPDATE 4:22 pm:

One lane is blocked on I-43 near Wisconsin Avenue exit. 

UPDATE 2:20 pm: 

I43 SB at Fond du Lac to reopen at about 2:30pm. 

The evidence canvass covered a long area of the freeway, necessitating the 2.5 hour closure.

ORIGINAL:

Sheriff’s deputies responded to calls about a shooting on the freeway in the Marquette Interchange near Highland Avenue today at about 10:10 AM.  More than a dozen shots were fired into a vehicle in an exchange of gunfire with another vehicle. One occupant was grazed by a bullet, according to Milwaukee County Sheriff's Department. 

Four subjects are in custody.  The Sheriff’s Office Criminal Investigation Division responded to four separate scenes where four vehicles were potentially involved in the incident.

• The male victim was driving a rental vehicle and stopped near 10th and Walker streets. Deputies recovered a weapon and arrested the driver and a male passenger. 
• MPD initiated a traffic stop at 17th and State streets on a vehicle with bullet damage and arrested two of the four occupants after a foot chase.  A subject abandoned a stolen car in the Marquette Interchange and fled on foot, and it is not yet known if he is involved in the shooting incident. Deputies found drugs in the car.  A fourth vehicle’s tire was blown out by a bullet and the driver exited at Plankinton Avenue. All vehicles were towed as evidence.
• I-43 southbound from Fond du Lac to Becher was closed for deputies to conduct an evidence canvass.  Shell casings and bullet fragments were recovered. Anyone who witnessed this incident is asked to call the Milwaukee County dispatch center at 414-278-4788.

Stay tuned CBS 58.