9:41 AM PT -- The Maryland Transportation Authority tells TMZ ... officers responded to the incident late Tuesday afternoon upon receiving reports of the fight. Officers identified five involved individuals, one of whom suffered minor injuries.

Meanwhile, a rep for Spirit tells us four employees of a third-party service they use have been suspended by that company pending an investigation into the brawl. Spirit says they do not directly employ the individuals.

The airline adds violence of any kind is not tolerated, and they plan to take appropriate action following the completed investigation.

A Spirit Airlines check-in counter spiraled into chaos when a heated argument turned into an airport beatdown ... and, it was all caught on video.

This crazy fight recently went down at Baltimore/Washington International Airport in Baltimore. It's not clear what led to the fisticuffs ... but, it seems one man was none too happy with the Spirit team -- and they matched his energy, ganging up on the dude and whooping on him.

Watch ... the dude squares up at the desk -- but, he's taken by surprise when a swarm of dudes -- who certainly appear to be Spirit employees based on their uniforms -- come running from behind the counter and start throwing punches, quickly laying the man out.

From there, the brawl turns into a good old-fashioned beating ... with the group of fighters landing a series of blows while the man is laid prone on the terminal floor -- where he's held down and punched/kicked.

For the most part, the video's pretty much just this group holding the other guy down ... before one of them lands a cheap shot right at the end.

Like we said ... it appears this fight's between a passenger and Spirit employees -- but, it's hard to say for certain. We've reached out to cops, Spirit and the airport about this incident ... but so far, no word back from anyone.

BTW, this is the latest in a stream of incidents at airport kiosks caught on video ... remember, last month a woman had a meltdown at LAX, berating the staff before realizing she was at the wrong desk. And, another person blew up about her period at a desk in January.

Fly safe everyone ... and, watch out for any potential brawls brewing. Put your dukes up!