Premise: A Philadelphia police officer is in the hospital being treated for an injury he suffered while chasing a suspect.The officer suffered a puncture wound to his arm.He was injured while responding to a 911 call at around 3:30 a.m. Sunday for gunfire near 30th and Cumberland in the Strawberry Mansion section of the city.When the officer tried to question a man in connection with the gunfire, the man made a run for it.The officer chased him and fell to the ground when he heard gunfire.The man got away.Police found several shell casings at the scene.------
Hypothesis: The gunfire was heard for 20 seconds.