Tamarris L. Bohannon, 29, was critically injured in the head while responding to a call of a live shooter on Saturday. The second officer was wounded in the leg by the shooter who then staged a 12-hour standoff before being apprehended, the St. Louis Metropolitan Police Department said.
They took to Twitter to announce the death of their colleague.
Bohannan had been a member of the police force for three and a half years, the police department said in another tweet.
The shooter, a 43-year-old white male, did not injure any other officers during the lengthy standoff. He is currently in police custody after medical evaluation. An investigation has been launched, the police force said.