An absolute joke was made of the booing of defender Harry Maguire in England's win over the Elephants.
Some fans booed as the name of the Manchester United captain was read over the tannoy.
Despite a difficult season with his club, he has been a mainstay in the team that reached the World Cup semi-finals and Euros final.
The reception was a joke, according to Southgate.
England claimed a comfortable victory thanks to goals from Ollie, Watkins, and Raheem, as well as the boos of some supporters.
The treatment of the 29-year-old was unacceptable and it was his 42nd appearance for his country.
I don't know how it benefits anyone. We are either all in it together or not.
If you asked a few of them why they did it, they probably wouldn't be able to answer. It is mob mentality. One end of the ground has a hardcore group trying to get his name sung.
Players will look at that and think that could be me. It makes them not want to come. It has happened before with John Barnes.
We need Harry to do well. We are not going to win a World Cup with a lot of players. That has never happened in the history of the game.
The way he has performed for us has been absolutely phenomenal.
He is in an England shirt and you should support a player in an England shirt even if you have not played at the level he has for us.
His performance was flawless. He stepped out from the back for the first goal and was involved in the second one. The team is united. He is a top player and he will come through difficult moments.
They are real England fans and some of them are influenced by social media or players who played before. He is in an England shirt, despite the club situation being very difficult.
I remember decades ago a few players were booed in England shirts and it was never acceptable to me. Fans should support their team.
The team-mates showed their support for him after the win.
Jordan Henderson said he couldn't get his head around what happened at Wembley. Harry was a colossus for England. The progress made at the last two tournaments would not have been possible without him.
He was booed at his home stadium. What have we become? What happened tonight was not right. I share a dressing room with him because I want to win with England. We all feel the same.
Jack Grealish pointed out that the booing was ridiculous as he called it.
The Manchester City player said that Harry has been brilliant for this country.
The first and second goals came from him driving with the ball and driving a little bit. Not every centre-back has those qualities.