UPDATE 7/23: The Southwest jet was removed from the runway overnight Monday, according to a statement from the airline. The three customers and crew members have been treated and released from local hospitals as of Tuesday morning.
The aircraft was last inspected on July 18, and entered service in October 1999.
Southwest said they are working with the NTSB and Boeing in the investigation of the incident.
EARLIER: The front landing gear on Southwest Airlines Flight 345 collapsed after the jet landed at LaGuardia Airport in New York on Monday afternoon.
A spokesman for the Dallas-based carrier said the pilot of the Boeing 737 with 150 people on board reported possible landing gear issues on approach to Runway 4.
The FAA said the plane was landing on a flight from Nashville at 4:45 p.m. CT when the nose gear collapsed as it was coming to a stop.
"The aircraft skidded down the runway on its nose and then veered off and came to rest in a grass area between the runway and taxiway foxtrot, about halfway down the runway," said Thomas Bosco, Acting Director of Aviation for the Port Authority of New York and New Jersey, which oversees the area airports.
Bosco said there was no advance warning of any possible problem before the landing,
A passenger, Sgt. 1st Class Anniebell Hanna, 43, of the South Carolina National Guard, said the flight had been delayed leaving Nashville. Passengers had heard an announcement saying "something was wrong with a tire," she said, waiting in a room at LaGuardia several hours after the incident.
At LaGuardia, "when we got ready to land, we nosedived," said Hanna. She and some family members were coming to New York for a visit.
"I hit my head against the seat in front of me," she said. "I hit hard."
First photos from the scene showed emergency vehicles spraying foam on the disabled aircraft.
Front and rear emergency evacuation chutes were deployed.
The Port Authority said 10 passengers were treated at the scene Monday night, with six being taken to a hospital with minor injuries. The six crew members were taken to another hospital for observation.
Bobby Abtahi, an attorney trying to catch a flight to Dallas, was watching from the terminal and heard a crowd reacting to the accident.
"I heard some people gasp and scream. I looked over and saw sparks flying at the front of the plane," he said.
Richard Strauss, who was on a nearby plane waiting to take off for Washington, said the nose of the Southwest jet was "completely down on the ground. It's something that I've never seen before. It's bizarre."
A rear stairwell or slide could be seen extending from the Southwest flight, said Strauss, who owns a Washington public relations firm. His plane, which was about 100 yards from the Southwest flight, wasn't allowed to taxi back to the gate, he said.
Southwest issued this statement:
"Southwest Airlines Flight 345 landed at New York's LaGuardia at 5:40 PM Eastern Monday evening from Nashville. The aircraft is a Boeing 737-700. Eyewitness reports indicate the aircraft's nose gear collapsed upon landing. There were 150 people on board including Customers and Crew. All Customers have been deplaned and transferred to the terminal. Initial reports indicate local responders are caring for five Customers and three flight attendants who have reported injuries at this time. Southwest is cooperating with local authorities, and the NTSB has been notified."
LaGuardia Airport was temporarily closed following the emergency, but one of two runways was operating shortly after 6 p.m. CT.
An investigator from the National Transportation Safety Board was on the way to New York to begin an investigation into what happened.
Monday's incident came 16 days after Asiana Flight 214 crash-landed at San Francisco's international airport on July 6, killing two Chinese teenagers; a third was killed when a fire truck ran over her while responding to the crash, authorities said. Dozens of people were injured in that landing, which involved a Boeing 777 flying from South Korea.
WFAA's Monika Diaz and Marcus Moore in Dallas and The Associated Press contributed to this report.