The fish are usually chasing eachother around the tank as well
The male's breeding tubercles are a little bit rough (kinda like sandpaper), so when he rubs his gills and pectoral fins against the female's belly he's encouraging her to lay her eggs. It's not uncommon that two or even three males are chasing one female around, though it's highly stressful for her.
If you want to save the eggs and have goldfish babies, the best thing to do is to separate a female and one or two males into a smaller breeding tank where you have prepared a spawning mop or some fine-leaved plants like Elodea or Hornwort for the fish to lay the eggs in
You can remove the adults afterwards and start caring for the eggs
It's good to add something mild, like Pimafix, against fungus into the tank since eggs are very susceptible to fungal infections and then they may be destroyed
Later you feed the fry 3 or more times a day with either specially prepared fry foods, reared artemia nauplii (you can buy hatching kits in the pet store) or you make your own fry food out of hard boiled egg yolk powdered into a small amount of water and mixed together before feeding