Head coach Lee Radford said the loss was "the worst" he has seen from the club, where he played more than 200 games before becoming coach in 2013.
"As a group they asked to have five, 10 minutes by themselves," Radford told BBC Radio Humberside.
"They obviously want to air a few grievances and sit down and find out what they want to do."
Radford continued: "Never in my reign have we given in like we did tonight - it's categorically the worst performance since I've been here."
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The defeat against Widnes was Hull's third consecutive loss, but it was the manner of the defeat that disappointed Radford.
Hull were 24-6 down at the break and failed to register another point in the match, leaving them seventh in the Super League table.
"I am responsible for tonight, I bear that," Radford said. "I'm looking forward to finding out what's been said (by the players).
"To put in that performance, with as little competitiveness as we did, I am solely responsible for that and I am solely responsible for fixing this up."
Hull FC players asked their coaches to leave the dressing room following Thursday's heavy 46-6 defeat by Widnes.