New England Revolution players refused to train on Tuesday in response to a lack of clarity over the circumstances that led to Bruce Arena's resignation as manager, multiple sources confirmed to ESPN.

The Athletic was the first to report the news.

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Arena resigned Saturday following a nearly six-week investigation by the law firm Proskauer Rose, which was hired by MLS to look into allegations of "insensitive and inappropriate remarks" made by the now former Revs manager.

Arena was initially placed on administrative leave, with the team being managed on an interim basis by assistant coach Richie Williams.

MLS, in a statement released Saturday, indicated the investigation "confirmed certain of these allegations" and that if Arena wished to work in the league again, he would have to file a petition to MLS commissioner Don Garber.

A report in The Athletic asserted that complaints filed by Williams were part of the investigation.

During Tuesday's media availability, Williams said the decision to not train was made by players and staff "as a group collectively."

But sources tell ESPN that during a meeting between players and staff, which included Williams, interim sporting director Curt Onalfo, team president Brian Bilello and a representative from human resources, players asked Williams to elaborate on the extent of his involvement in the investigation.

When Bilello indicated that they couldn't respond to that question, the players reacted negatively to the lack of transparency and decided they wouldn't train.

A second meeting between players and the coaching staff took place afterward in which Williams once again said he couldn't answer their questions.

The circumstances surrounding the investigation into Arena and his eventual resignation threaten to turn a once-promising season into turmoil.

With Williams in charge, the Revs have gone just 1-1-3 in league play, with another two draws in the Leagues Cup. New England remains in second place in the Eastern Conference with 48 points from 27 matches, nine points behind first-place FC Cincinnati.

Sources have also told ESPN a schism has developed within the staff, with assistant coaches Shalrie Joseph and Dave van den Bergh firmly in Arena's camp. Their future with the team is unclear at this point.

When asked about how united the staff was, Williams responded: "Just in terms of the staff, with me personally as the interim head coach, they've asked me to take over, to be the coach until the end of the season, hopefully into the playoffs and to a championship, and that's obviously what I'm going to be doing moving forward.

"And again, it's been a very good response over the last six weeks from the players and with results-wise and maintaining our second-place standing in the league."