Police say the shooting happened during a fight between two groups that police attempted to break up. Police say the officer was off-duty.
Denver Police Chief says they do have a person in custody but stopped short of calling that person the shooter.
The shooting occurred shortly after the Jazz in the Park concert series ended around 8 p.m. Hundreds attended the event, including families and children. Mayor Hancock's wife and child also attended.
A 9NEWS employee, attending the concert, heard the shooting and saw several people run towards the south side of the park.
Police say the single mother was in her 30s and had been with the department since 2005. She covered the Jazz in the Park concert series for several years.
9NEWS has confirmed the name of the officer, but is withholding that information until her family has been notified.
Witnesses told 9NEWS that an ambulance was on scene within 5 minutes and transported the wounded officer to Denver Health.
Denver Mayor Michael Hancock and Denver Police Chief Robert White made a statement outside Denver Health Sunday night.
They called the fallen officer dedicated, a leader in the department. Mayor Hancock said the city will come together.
"We will put our arms around this family and this child, and make sure they know there is a city that absolutely loves them," Hancock said.
Police were seen searching a dumpster near a lake Sunday night.
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