Officers said the shooter was standing outside and fired several rounds towards the door and window. A victim was asleep in the living room when she was hit.
Detectives said they have little suspect information because they were delayed in getting there.
"People heard shots fired but they did not call the police, because that caused a time lapse in us getting here," said Lt. Joe Gomez with the Fresno Police Department.
Police found the apartment covered in blood.
The woman was hit in the leg and is expected to recover.