A Chicago police officer was unintentionally shot and killed by her partner after they chased a suspect into an apartment and encountered another person with a rifle, officials said.

A Chicago police officer is in critical condition after being shot on the South Side late Thursday night. The incident occurred in the East Chatham neighborhood, prompting a swift response from fellow officers who rushed her to the University of Chicago Hospital.

Three people were killed in shootings across Chicago during the extended Memorial Day weekend, making it one of the least deadly holiday weekends in the city in recent years.