"I immediately yelled out, 'Police! Drop the knife,'" Officer Jason Sommerville of the 39th District said.
The incident took place at Broad Street, south of Lehigh Avenue.
Officer Sommerville spotted one man attacking another with a knife.
Sommerville chased the suspect down through heavy traffic on Broad Street.
After a brief fight, he had 47-year-old Harold Cooper in custody.
The victim, 32-year-old Matthew Bullock, died as a result of the stabbing.
Cooper is said to be another career criminal willing to take on an armed cop.
"Now, people just have a heightened level of lawlessness and disregard for the law and all authority," Officer Sommerville said.
Officer Sommerville did know Officer /*Pawlowski*/. They were together in the police academy together.
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