[UPDATE BELOW] It sounds like there's a major headache for some commuters trying to get to JFK airport this morning. The AirTrain that runs from Jamaica station to the airport has been shut down. According to a Port Authority spokesman, an "unknown liquid" was found "leaking out of a broken glass tube" at Jamaica station. It's unclear where exactly the tube was found, but Port Authority police and MTA police have established a 100-foot perimeter around the scene, and a HAZMAT team is investigating.

One tipster who tried to get to JFK via the AirTrain tells us "MTA and Port Authority police are everywhere, and they're putting everyone on shuttle buses to Federal Circle. Buses are not handling the load well. Probably 100+ people fully loaded with luggage [waiting] on line. I got a cab for $12.50 for the short ride to JFK."

We'll update as more information becomes available.

Update 11 a.m.: Port Authority spokesman Al Della Fave tells us that AirTrain service has resumed. At 10:41 a.m., the "all clear" was given after the substance was deemed non-hazardous. Della Fave says the HAZMAT team was called in because the "material was coming out of a broken test tube on the Jamaica station platform." No word yet on what exactly it was.