A driver involved in a west Phoenix crash that killed a 4-year-old boy and seriously injured his 2-year-old brother has been released, Arizona Department of Public Safety officials said Wednesday. The crash happened shortly after 11 a.m. Tuesday on eastbound Interstate 10 near 43rd Avenue. DPS said a Dodge Challenger struck the rear of a Toyota Corolla, pushing the Corolla into a Chrysler Pacifica. The boys were riding in the back of the Corolla, driven by their mother. The 4-year-old, who was properly buckled in, was hospitalized and later died. His younger brother was seriously hurt. Their mother was not injured. The older boy has not been publicly identified. DPS said the Challenger driver will be referred through a long-form complaint alleging distracted driving. The document lays out allegations for possible criminal proceedings and is more detailed than a standard traffic citation. Authorities have not said what distracted the driver or what led to the collision. The Maricopa County Attorney’s Office will decide whether to file charges. The driver’s release does not resolve that decision.