MESA, AZ — Arizona Department of Public Safety officials say a crash along Loop 202 Santan on Thursday afternoon left a woman and her unborn child dead.

The crash happened on the westbound Power Road off-ramp around 3 p.m. when a large work truck struck four vehicles from behind.

One of the vehicles was pushed off the roadway during the collision, killing the unnamed driver and her "full-term unborn child."

Officials say the truck struck the vehicles when it failed to stop for traffic congestion.

The investigation is ongoing.