At least two people were killed and dozens were injured.
The Greyhound bus was carrying 45 passengers from Los Angeles to San Francisco when the attacker struck.
Police said one man, possibly helped by another, rose from his seat and slashed the driver with a knife.
Emergency workers found 10 people with critical injuries lying in the wreckage in a cotton field near Fresno.
“This was not an accident,” Sheriff’s Lieutenant Jeff Johnson said. Officials said the attack was not related to terrorism.
Lt Johnson said the alleged attacker was arrested, apparently after trying to run from the scene.
Authorities originally said the driver was one of the two dead, but Fresno County Sheriff Department later said he had survived the attack.
“The suspect attacked the driver of the bus with a knife. The driver was actually cut in the neck,” said Lieutenant Margaret Mims.
“He struggled, tried to defend himself and lost control of the bus.”
A year ago, a passenger on a Greyhound bus in Tennessee cut the driver’s throat, causing a crash that killed seven of the 40 people on board.
Lt Mims said the FBI was not involved in the investigation and the attack did not appear to be any sort of terrorist act.
“If somebody is thinking terrorist or hijacking or anything like that, we don’t have any reason to believe that’s the case,” she said.
There was no word on what the motive might have been for the attack or if other vehicles were involved as the bus crashed.
California Highway Patrol spokesman Tom Marshall said one man had been arrested and there was some concern the alleged attacker may have had an accomplice.
A Greyhound spokeswoman said a hotline had been set up for friends and family members of passengers to call for information.
“Our top priority right now is taking care of all of the passengers as well as the driver and their families,” she said.