CHICAGO (CBS)–Interstate 57 was shut down last night after a 55-year-old postal worker was fatally shot on the highway in the northbound lanes when someone in another vehicle opened fire.

Tarmara Clayton-Shelton was shot to death in her vehicle as she was driving north on I-57 near Cicero Avenue shortly after 10 p.m., not far from her home in Country Club Hills. Police sources said the shooting might have been a case of road rage.

READ MORE: 1 Killed, 4 Injured In Evanston Shooting

Tarmara Clayton-Shelton, 55, was shot and killed on Feb. 4, 2019, while driving on Interstate 57, not far from her home in Country Club Hills. (Source: Facebook)

Clayton-Shelton worked for the U.S. Postal Service for more than 25 years, and was a mail handler at the Chicago International Military Service Center facility near O’Hare International Airport.

“The Postal Service is deeply saddened on hearing of this tragedy and share our thoughts and prayers with the family,” Postal Service spokeman Tim Norman stated in an email.

The fatal shooting marked the second time gunfire erupted on the highway on Monday. More than 40 shootings have been reported on the highway during the past three years, the worst area for expressway gun violence in Chicago.

In Monday night’s shooting, police recovered shell casings on the expressway, a portion of which was shut down for more than three hours so troopers could gather evidence and process the murder scene.

READ MORE: At Least 40 People Wounded, 3 Killed In Thanksgiving Weekend Shootings In Chicago

About six hours earlier and about six miles away, two young boys and a man were shot while they were riding in a Hyundai Tucson.

The man, 38, is in critical condition Tuesday morning.

The two boys, ages 15 and 12, are both in stable condition.

The shooting happened just after 4 p.m. in Calumet Park on the interstate near 127th St.

An eight-year-old girl who was also in the car was not shot, but was taken to the hospital in stable condition.

At this point, police are not saying what led up to either shooting.

MORE NEWS: Wolfpack Junior Football Team Needs Funds To Compete For National Championship In Florida

No one is in custody.