At least 10 people were injured, according to the Port Authority of New York and New Jersey, which operates the airport; six of those were taken to Elmhurst Hospital Center. The extent of their injuries was not immediately known, though it appeared that none were serious.
The airport was closed for about 80 minutes, and partially reopened at 7:06 p.m.
The plane, Flight 345 from Nashville, had 150 people on board, Southwest said in a statement.
The authorities did not immediately indicate the cause of the accident.
“The plane’s nose gear collapsed as the aircraft landed on Runway 4 at 5:45 p.m.,” Kathleen Bergen, a spokeswoman for the Federal Aviation Administration, wrote in an e-mail.
Photos of the plane showed its nose resting on the tarmac surrounded by emergency vehicles. The plane’s rear landing gear appeared to have deployed normally.
Witnesses said the landing seemed normal until the front landing gear hit the runway.
“I saw a tire fly off and go to the left and the nose hit flat on the ground, and sparks went flying everywhere,” said Jeff Crabiel, 30, a hotel worker from Nashville who was aboard a Delta Air Lines flight that was on the runway.
Airport officials said emergency personnel were not aware of any problems before the plane landed.
“It didn’t appear that anyone was waiting for this plane to arrive like that,” said Bobby Abtahi, 31, an lawyer from Dallas who saw the landing from inside the terminal.
After the plane came to a stop, Mr. Abtahi said, emergency vehicles emerged from nearby garages and raced to the scene.
By then, he said, the plane’s inflatable slides had deployed, and passengers were rushing out.
Officials said the airport would not be fully operational until at least Tuesday morning.
Mr. Abtahi said airport officials initially provided little information about what was happening, even as crowds of passengers gathered at the terminal windows to watch.
“I was learning more on Twitter than I was hearing on the loud speaker,” he said.