A Port Richmond man is in custody after he carjacked a 73-year-old man’s vehicle near 52nd and Chestnut yesterday afternoon and was chased by witnesses who alerted police.

Police say 33-year-old Hadbin Austin of the 3100 block of Janney Street wielded a 10-inch knife and wrenched the man from his 2011 Kia at about 3 p.m. Police said the victim was eating food he purchased at the nearby McDonald’s.

Austin smashed into another car, flattening one tire on the Kia. Several witnesses observed the incident and called 911, police said. As many as three people pursued Austin until he abandoned the vehicle near 40th and Market. The pursuers alerted police to the car’s location and officers apprehended Austin after a brief struggle.

Austin has been charged with aggravated assault, robbery and related offenses. Police said the victim was not injured in the incident.

The Daily News reports that three people, two employees of Verizon and one SEPTA worker, pursued Austin and helped lead to his arrest.