Is it legal to arrest someone without a warrant then tell that they will just come back when they have it?

My son didn't know he had a warrant for his arrest. He was short 10 hours of community service. He went to a Christmas party and took taxi home. He told the driver he needed to go into house and get the money. He forgot his key and took over 5 minutes to wake up sister to get money. He went to pay and the taxi was gone. Taxi called police/sheriff and they saw that he had a warrant and they came out to our house. Three sheriffs pounded on our door and I was still in bed and my wife just woke up. She answered the door and they asked my wife if my son was home and she said that she didn't know and that she would go look and asked to shut the door. They put their foot in the door and said no and then slammed the door in my wife’s face and threw her to the wall and went and got my son who was already asleep. They took him to jail. My wife asked for a warrant and they didn't have one. My wife said that she was going to call 911 and they said, that's okay, they will just go get the warrant and come back. Is what they did legal? We have pictures of my wife’s face. Busted lip and swollen left cheek!