A woman was fatally shot Monday afternoon on I-20 westbound near I-285 in southwest Atlanta.

“We do not believe it’s a random act of violence, nor do we believe it’s road rage,” Atlanta Police Capt. Paul Guerrucci said. “We believe that whoever is involved all knew each other one way or another.”

The woman, who was found shot at least once in a car that was pulled over to the left shoulder of the interstate, was transported to Grady Memorial Hospital, where she died, police said.

The woman, who appeared to be in her mid-20s, has not been publicly identified. Authorities are speaking to the woman’s passenger, who Guerrucci said is cooperating with police.

Police were called to the scene on I-20 westbound near I-285 southbound around 3:40 p.m. after a passerby called 911, Guerrucci said. They found the woman shot in a silver Volkswagen Passat, but police said they believe the woman and the shooter were outside the vehicle when the shooting occurred.

Police have not determined a motive.

Two left lanes of I-20 westbound were closed near I-285 southbound as part of the investigation, backing up traffic for hours.

Anyone with information on the shooting should contact Crime Stoppers by calling the tip line at 404-577-TIPS (8477), going online at www.crimestoppersatlanta.org or texting CSA and the tip to CRIMES (274637). Tip contributors can remain anonymous and be eligible for the reward of up to $2,000 for the arrest and indictment of the suspects.

Staff writer Angel K. Brooks contributed to this article.