Aston Villa manager Tim Sherwood said his side's first-half display at Southampton "hurt" and was the worst since he took over.
Sadio Mane scored the Premier League’s fastest-ever hat-trick as the hosts ran away to a 5-1 half-time lead, before Graziano Pelle completed the rout late in the second half.
Hull’s defeat at Tottenham means Villa have secured Premier League survival despite the defeat, which Sherwood said was due to his players "switching off".
"That's the game, that happens,” he said. “You see it time and time again, you switch off. You need to stem the flow and stop the bleeding, unfortunately we weren't able to do that until the game was over."
"I am disappointed - disappointed that the 45 minutes of football there was not good enough.
"We feel very sorry for our travelling fans who stuck with us right until the end and Aston Villa fans around the country and around the world.”
Sherwood has made a strong impact since taking over in February, guiding his side to the FA Cup final and lifting them out of the relegation zone to safety with a game to spare.
"Since I've been in the club those are the only 45 minutes I can complain about,” he added.
“We have to not get too carried away and put it behind us as we have no choice but to move on to our next game which is Burnley at home.”
"Credit to Southampton, they punished every mistake we made. We made quite a few as a group.
"I'm not just talking about defenders, midfielders, attackers - the coaching staff, everyone who was involved at this football club has to take responsibility and we do. It wasn't good enough.
"We've done brilliantly over the last couple of months, we've been fantastic and that's why we can't get too carried away with this, it was a defeat, it was a heavy defeat and it hurts everyone."