Negotiators for the NFL and locked out players continued to make progress toward a deal Thursday as they met in New York to end the sport’s nearly four-month shutdown, according to several people who are familiar with the talks.

The two sides were attempting Thursday to resolve the central economic issue of the dispute: how to divide the sport’s revenue, currently about $9.3 billion annually but expected to rise sharply in coming seasons, according to the people, who are not part of the negotiations. They spoke on the condition of anonymity because of the sensitivity of the discussions.

Full negotiating teams for both sides met for the first time this week. They gathered at a Manhattan law office and there were indications that the negotiations could continue into the night.

It was not clear whether the league and players would be able to resolve their differences in the next few days. The talks are scheduled to continue at least through Friday, with tentative plans to continue into the weekend if necessary. The court-appointed mediator who is overseeing the deliberations, federal Chief Magistrate Judge Arthur J. Boylan, is scheduled to leave Saturday on vacation, but the talks could continue without him.

People across the sport remained wary that the talks still could stall or unravel completely. The talks nearly collapsed last week in Minnesota.