SOUTH PORTLAND — Police say excessive speed is being investigated as the cause of a single-car crash Monday night that caused the death of a 20-year-old Southern Maine Community College student.

Police said Patrick Donaghue, of Wilton, was a passenger in a vehicle that crashed through a wooden guardrail near the entrance of Bug Light Park. He was not immediately identified.

Police said no charges have been filed against the driver, William Blanchard, an 18-year-old SMCC student from Gorham, who called police from the scene around 9:20 p.m.

The crash remains under investigation. State Police are assisting local departments with crash reconstruction, and a vehicle autopsy is anticipated.  Once the investigation is complete, the District Attorney’s office will make the final determination on whether Blanchard will be criminally charged, according to a press release from South Portland police issued Friday.

Responding officers found a 2004 Volvo sedan had gone off Madison Street and landed on a grassy area of the park. The driver was with the vehicle, police said, and the victim was unconscious inside.

The victim was taken to Maine Medical Center in Portland, where he died of his injuries around 3:30 a.m. Tuesday, according to police.

The driver was also taken to the hospital, treated for injuries and later interviewed by detectives. State law also requires that drivers involved in fatal accidents have their blood tested for alcohol and other substances.

The crash is being investigated by the South Portland Police Department with assistance from the Maine State Police.