8:05 AM PT -- Williams' attorney, Alex Spiro, says in a statement the arrest all stemmed from a "technical issue."
"Mr. Williams respects and follows the law," Spiro said. "There was allegedly a technical issue with the manner in which the lawfully owned firearm was stored -- and we expect the matter to be resolved shortly."
6:48 AM PT -- The Jets just released a statement on Williams' arrest, saying, "We have been in contact with Quinnen Williams and are fully aware of the situation."
"We will have no additional comment as this is a pending legal matter."
6:10 AM PT -- Sources tell TMZ Sports the gun was NOT loaded ... but one 15-round high capacity magazine was discovered in the luggage he was checking.
We're told Williams was headed to Birmingham, AL.
New York Jets defensive lineman Quinnen Williams was arrested at LaGuardia on Thursday ... cops tell TMZ Sports the former 1st-round pick brought a gun to the airport.
Law enforcement sources tell us Williams was going through a security checkpoint at around 9:15 PM ET when TSA agents scanned his luggage and found a Glock 19.
The way it was put to us ... Quinnen told officials he believed he could carry the gun into New York legally ... since the 22-year-old does have an Alabama permit for the firearm.
But, after authorities explained to the 6'3", 303-pound NFL player he had to have an NY permit to carry there ... they arrested him on a charge of criminal possession of a weapon.
We're told Williams was issued a summons ... and will be forced to appear in court later this month.
Quinnen was a MASSIVE star coming out of the Univ. of Alabama ... he was the No. 3 pick by the Jets in the 2019 NFL Draft.
Williams played in 13 games for NY this past season -- starting nine of them -- and he recorded 2.5 sacks with 28 combined tackles.