Three people were killed Thursday afternoon when a semi-truck plowed into slowing traffic on Interstate 44 near Southwest 119th Street in southwest Oklahoma City, triggering a chain-reaction crash that left one vehicle engulfed in flames.

The crash happened at approximately 3:15 to 3:30 p.m. on Aug. 20, according to the Oklahoma City Fire Department and Oklahoma City Police.

Oklahoma City Police Master Sgt. Rob Robertson said at a press conference near the scene that a semi traveling on I-44 failed to slow down as vehicles ahead braked for traffic. The semi struck the vehicle in front of it, which then hit the next car in what Robertson described as a domino effect.

"The semi-truck then rolled off to the side into the bar ditch. One of the vehicles was completely engulfed in flames, and as of now we have three fatalities," Robertson said.

Five vehicles total were involved, according to Robertson. Two of the people killed were in a pickup truck. The third person killed was in the semi.

The semi was carrying hazardous materials, News 9 reported, though the type of hazmat aboard was not specified.

A Chickasaw Nation Lighthorse Police officer was also injured in the crash and transported to a local hospital. Robertson said the officer is expected to recover. Officials did not say what role the officer's vehicle played in the collision or whether the officer was responding to a call at the time.

All eastbound lanes of I-44 at Southwest 119th Street were closed for hours following the crash, according to KFOR. Oklahoma City Police held the press conference at an On Cue convenience store near the scene, KFOR reported.

Oklahoma Attorney General Gentner Drummond acknowledged the crash on X on Thursday evening, saying he and his wife are praying for the injured officer and the families of those killed.

Police had not released the names of the three people killed as of Thursday evening. The total number of people injured beyond the Lighthorse officer was also not disclosed. The cause of the crash remains under investigation.