A knife-wielding man who attempted to hijack a tree-trimming truck in San Diego County died after the vehicle’s owner fought back, authorities said.

Suspect Mark Douglas Heninger, 56, allegedly tried to steal the truck while it was moving early Saturday morning in the 200 block of South Pacific Street in San Marcos, according to the San Diego County Sheriff’s Office.

Investigators said Heninger jumped into the truck while waving a knife. The driver immediately fought back, causing the suspect to fall from the truck and onto the roadway.

The truck driver called 911 and remained at the scene while paramedics treated Heninger, who was taken to a local hospital and later died of head trauma.

The driver suffered minor injuries but declined medical treatment.

Video from the scene showed the tree-trimming truck belonged to a company called Blue Wave Tree Care.

The sheriff’s office said alcohol or drugs do not appear to have been factors in the incident. The medical examiner’s office is still expected to determine Heninger’s cause of death. 

The suspect’s motive remains undetermined as homicide detectives continue to investigate the incident. 

A man with the same name and age as Heninger has a lengthy criminal record dating back to 1996, according to court records found. 

Anyone with information about the incident is encouraged to contact the SD County Sheriff’s Office.

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