Winston Perez, 28, of Riverside was working at the Dick Dykstra Dairy in the 10100 block of Schaefer Avenue just after 5 a.m. Saturday when he was crushed between a gate and fence by the cows.
He died at Arrowhead Regional Medical Center in Colton at 4:36 p.m. after undergoing surgery for severe internal injuries.
California Occupational Safety and Health Administration investigators say the business is fully cooperating with the investigation.
A man at the dairy on Monday declined to comment on the incident.
"We had an accident here, and that's all I'm going to say," the man said, declining to give his name.
The dairy sits east of Archibald Avenue at the end of an unmarked stretch of Schaefer, within Ontario's agricultural preserve.
"This investigation can be timely," said Cal/OSHA spokesman Peter Milton. "It's very thorough and the dairy seems to have a clean safety record."
Officials said it's very rare a business is shut down following an industrial accident such as this.
"If equipment poses an immediate danger then we shut that equipment down," Milton said. "But I don't recall ever shutting a business down following an accident where a life was lost."
Despite the severity of the incident, some workers at nearby dairies had not even heard about it.
The owner of a dairy on nearby Vineyard Avenue who declined to give his name said workers getting crushed by cattle is not common.
"If a cow decides that it wants to charge, it's going to charge. You just keep your distance," he said.
All businesses in California investigated by Cal/OSHA are in an online database that is accessible to the public at osha.gov.