PHILADELPHIA - A Philadelphia police officer who was injured during a gunfight with a man accused of shooting and killing a co-worker at Jefferson University Hospital earlier this month was released from the hospital on Wednesday.Officer Arcenio Perez was hit in the arm with a rifle round when he and three other officers were allegedly fired upon by Stacey Hayes in the schoolyard of School of the Future on the 3800 block of Lansdowne Drive, according to investigators. RELATED COVERAGEAuthorities say Hayes, 55, entered the hospital around midnight wearing scrubs and a mask and carrying a bag of guns.