The clinic is located on the corner of Clinton and Maple Aves. The accident happened around 10:30 a.m.
Capt. Dave Paris, of the California Highway Patrol, said the driver of a white pick-up was heading west on Clinton Ave. and ran a red light. It crashed into a tow truck, carrying a car on its bed. The tow truck was driving south on Maple.
"The force of the impact sent both vehicles southward," he said. "The pick-up struck the light pole; the vehicle crashed through the walls of a medical facility and came to rest in the lobby."
A medical assistant, working behind the counter at the time of the crash, told Action News there were about a dozen people inside the building. She said the force of the crash was so powerful it threw some people across the waiting room.
"The chairs were all pushed out and we didn't know if there were people in the bottom of the truck, or they were okay, because the truck was blocking everything," she said. "(It was) Scary, too many things were going through my head, I couldn't think. I just wanted to make sure everyone was alive."
Paris said five people were taken to Community Regional Medical Center with moderate injuries, are expected to be okay.
"We're very fortunate that those people inside did not get impaled by the vehicle or other debris," Paris said.
Paris said the driver of the pick-up truck and the tow truck had minor injuries. But he added that the situation could have been much worse had there been a passenger in the tow truck.
"Portions of that building we're impaled through that building into the seat," he said. "That would have caused serious, fatal injuries."
The accident resulted in some lane closures along Clinton and the northbound lanes of Maple for several hours.
Traffic Crews had to close the southbound lanes of Maple for several hours, while crews cleaned up the scene. All lanes are now open.
City workers also had to replace the traffic light pole. It was resting against a tree and emergency crews say it could have easily tipped over into the sidewalk or street causing more injuries.