BOSTON — Police are crediting civilians for helping apprehend a man who allegedly carjacked a woman on a Boston street.

Authorities say 36-year-old Joel Cartagena grabbed the medical student’s hair on a street in the South End at about 3:20 p.m. Thursday and threw her into the passenger seat. He then drove off but crashed a couple of blocks away.

A civilian witnessed the crash and told nearby utility workers, who alerted an officer working a detail. The civilian followed Cartagena until police caught up.

Cartagena told police it was the woman’s fault.

The woman was treated at a hospital for minor injuries including a bloody nose and bruises.

Cartagena is scheduled to be arraigned Friday on a variety of charges including kidnapping and carjacking.