According to Washington State Patrol, both collisions happened after a vehicle slowed down and was hit from behind.
Troopers say a 37-year-old Benton City woman was driving west on Highway 240 just before 4 p.m. when she slowed down for a dog in the road. A car being driven by 51-year-old Gillermina Rodriguez of Sunnyside failed to slow down and hit her car.
A 26-year-old Grandview woman, a passenger in Rodriguez's car, was taken to Kadlec Medical Center for observation.
WSP says the second crash happened around 4:15 p.m. in the same area. A 29-year-old Pasco woman slowed for traffic when 49-year-old Miguel Silva-Hidalgo of Yakima hit her car from behind.
Two passengers in Silva-Hidalgo's car, a 49-year-old Pasco woman and a 16-year-old Yakima girl, were taken to Kadlec
Rodriguez and Silva-Hidalgo were both cited for driving too fast for conditions.
Troopers say drugs and alcohol do not appear to have contributed to either crash.