The first crash occurred at Rowell and Olive avenues, where officers say a vehicle turned in front of the rider, hitting them.
That motorcyclist was taken to the hospital with major injuries.
The driver is cooperating with authorities.
While officers were investigating that crash, a second motorcyclist was hit in a separate incident nearby at Cedar and Olive avenues.
Authorities say the second rider was also taken to the hospital and is expected to survive.
No additional details were immediately released.