A spokesperson for the league told TMZ Sports on Tuesday they're "monitoring" the situation ... although no further details surrounding their probe into the matter were given.

As we previously reported, two high-end cars -- a Lamborghini and a Corvette -- caused a huge pile-up on an expressway over the weekend, after they were seen speeding in and out of traffic. None of the passengers of the cars, cops say, stayed on the scene to see if anyone needed medical help.

According to the Dallas Morning News, one of the vehicles involved was registered to Rice ... and cops were actively looking to speak to him in the aftermath of the wreck, although the Chiefs star has not been formally accused of a crime.

The 23-year-old's attorney said in a statement on Monday afternoon the wide receiver was cooperating with local authorities. Cops also confirmed they had been in contact with Rice's legal counsel ... "but have not conducted interviews with potentially involved individuals in Saturday's crash."

As for Kansas City, team president Mark Donovan said on a local radio show Monday morning they're working to "get to the bottom of it" all.

"We'll gather the facts," he added, "and then we'll react accordingly."