NFL Players Association executive director DeMaurice Smith and his group left shortly before 8 p.m., 52 hours before the current collective bargaining agreement is due to expire.
Mara, Atlanta Falcons president Rich McKay, chairman of the league's competition committee, and Washington Redskins general manager Bruce Allen were among those joining NFL Commissioner Roger Goodell when mediation resumed Tuesday at 1 p.m.
It's the eighth day of mediation between the sides.
The CBA runs out at midnight as Thursday becomes Friday on the East Coast.
